TSA Agents Amanda Zug, Supervisor Shawn Knaub and Manager Kendall Bradley provide a teachable moment in cross-contamination and the need to adhere to contamination protocol


Yours truly being subjected to an enhanced pat down due an invalid IonScan result

I begin this post with a declaration and acknowledgment upfront. I am a Trusted Traveler. I went through the application, background check, and less to obtain my Global Entry ID. I have said publicly and I continue to do so now, that I enjoy being a Transportation Safety Administration (TSA) pre-check customer. It is a good program. While some people decry that the TSA is simply theatrics, an over bloated and ever expanding monster bureaucracy whose results do little to stop, halt or deter those who are determined to do harm while traveling, I am not one of those folks. As a general proposition, I find the people to be working at TSA to be well intentioned and truly believe in their heart of hearts that they are doing the right thing to keep us all safe.

However, on Wednesday December 17, 2014 at the Harrisburg International Airport (MDT), I personally encountered an alarming incident. I am trying my best to put aside the personal feelings I have over the way this incident went down to instead provide a teachable moment. This incident, which is on video that I captured, provides for a teachable moment for those who follow this blog and enjoy applied forensic science.

Also as a declaration, I have taught (and still teach) at Axion Labs and the American Chemical Society (ACS) about the Smith’s Detection IonScan devices (both the 400 and the 500DT) and Ion Mobility Spectroscopy (IMS), which is the underlying scientific principle upon which this device operates. I have a pending peer review article on its validity (or lack thereof) when it comes to cocaine detection as currently deployed by the Northeast Counterdrug Training Center (NCTC) and the Counterdrug Joint Task Force (CJTF) in Pennsylvania. I have litigated against this device and those operating it. As a result, District Attorneys Offices have refused to offer the results of the device into evidence and one judge did not allow its results into evidence in a particular case for issues including lack of specificity, lack of traceability, lack of the adherence to the 5 Q’s, lack of a validation study, lack of a validated protocol, and lack of adherence to Instructions (Standard Operating Procedures). I have extensively litigated Right to Know (Pennsylvania’s form of FOIA) claims to get a tremendous amounts of information on the device, its operation and its training of its operators. I have received affidavits attendant to the device, its application, and training. I have received and reviewed numerous government expert reports on the device. I have a copy of the Smith’s Detection Ion Scan Operational Manual (both the 400 and the 500). I have tried to receive operator training, but have been denied. I am about as familiar with this device as any scientist can be.

This Incident:

The People Involved

  • Justin J. McShane, JD, F-AIC: me, traveler and citizen
  • Alex Duffie: traveler and citizen. I did not know Alex before the TSA checkpoint.
  • Amanda Stanton Zug: TSA Screening Agent
  • Shawn Knaub: TSA Supervising Screening Agent
  • Bradley Kendall: TSA Manager

The Location

  • Harrisburg International Airport (MDT) Middletwon, PA

The Facts:
It all began with my travel plans on December 17, 2014 to go to Chicago ORD via MDT on a carrier. I was traveling with my fiancé. It was among the first flights out in the morning at MDT. As is the case at MDT with the first flights out in the morning, MDT is much busier than normal. Normally, when one comes up to TSA at MDT there is not more than a 4-person line. It is pleasant. As I fly a lot, some of the TSA know my face. I have always found them to be professional.

This morning (12-17-2014) when I came to MDT and to the TSA checkpoint, there was a line (but significantly less than any other airport I have encountered). They appeared to be appropriately staffed.

I was granted TSA pre-check. Unlike other TSA pre-check facilities, MDT has a partial pre-check program whereby the person subject to screening does not have to go through the backscatter X-ray device (see our post on the limitations on the use of Backscatter technology), but instead a metal detector. At this location, a TSA pre-check person still has to completely remove his or her laptop and place it in a bin for the x-ray machine (traditional x-ray, not backscatter). I did so efficiently and with no complaint.

I went through the metal detector. My bag made it through. So did my coat and boots (the boots always set off the metal detector). My laptop (along with some other people’s items) was randomly chosen for enhanced screening.

A young gentleman (after this was all over, I asked for his name to document all of this, he was happy to provide it) who I did not know and who was separately traveling arrived to MDT TSA checkpoint two people ahead of me in the enhanced security area. He decided to bring along 2 bottles of eye solution/contact lens solution in his carry-on. One and been previously opened by the passenger. The other was in its completely sealed box with its tamper evident seal on the cap. As they were declared and as they were separately placed in a bin they were permitted per current TSA guidelines. However, as it liquid it was subjected to an enhanced screening check for volatile organic compounds (VOCs).


An example of the boxed and tamper evident seal of Alex Duffie’s eye/contact lens cleaner (Item#2)

As I am interested in applied analytical/forensic chemistry, and as I was two behind him and awaiting the release of my laptop, I watched the examination of Alex’s two items. The items were presumably placed in the bin by Alex. Alex’s liquid is identified at the x-ray and placed with the other items for random or enhanced screening. They were physically moved from that line of enhanced item check line by a lady screening agent whose name I did not get (definitely not Amanda Stanton Zug).

If you have ever been selected for random additional screening or have carried liquids, you know that the examination is conducted in the same area, which is a steel desk.

This unidentified lady TSA agent employed the “vapor phase test strips” on Alex’s two liquid items. They do so using a reagent after holding the testing strip above the liquid to capture presumed headspace (yet unspecific as to source obviously) above the screened liquid.

First for testing was the opened box of solution. I watched in detail as it was deployed. The reagent was applied. No color change. It was released. They asked him to open the still boxed and unopened box including moving the tamper evident seal. He complied with the request. The headspace VOC analysis using the vapor phase test strip was conducted on this box. The reagent was applied and it turned blue (it was announced as a “hit for explosives” by the unidentified lady TSA agent which I suppose she meant that it was presumptive screening positive for explosives). Alex looked confused. The unidentified lady TSA agent performed another test. It too turned blue. Perhaps sensing the confusion and alarm of some, the unidentified lady agent looked at the ingredients and noted out loud that it had hydrogen peroxide which she stated was a known false positive creating agent. [Blogger’s note: The unidentified lady TSA agent kind of right in the context of the application, but technically scientifically, it is not a false positive. The strip used is actually selective for any form of peroxide. Hydrogen peroxide has been used for creating organic peroxide based explosives, such as acetone peroxide. So that is the issue and perhaps why this particular reagent strip is used.] Alex was told that he had to have a pat down. Before he was removed to the separate pat down area, Alex was asked/ordered to remove everything from his pockets. He promptly did so putting everything on the testing desk where the opened Item#2 remained with its VOCs going everywhere in the immediate area. Someone picked up Item#2 to conduct a Smith’s Detection Ion Scan (in TSA parlance they call it an ETD or Explosives Trace Detection test). Not surprisingly to anyone who understands and knows IMS technology that the Smith’s Detection Unit is based upon or the actual 400/500 device, the bottle also alarmed as it is not sufficiently selective to discern H2O2 (hydrogen peroxide) from HMTD (peroxide based explosive), and TATP (peroxide based explosive).

According to Smith’s Detection (formally Berringer) literature, this is what the device detects:

Ion Scan 500

According to the published evaluation literature, here is the detection limits for various compounds:

Explosives mode

According to the patent (US Patent US20080101995 A1), we find this:

Table 1

Further in the art we see this very clear declaration of limitation on the device:

false positive

It is clear that this device is not sufficiently specific to resolve between H2O2, which is allowed on planes, and peroxide based explosives. It is selective for peroxides only.

Next to enter the picture was TSA screening Agent Amanda Stanton Zug. Prior to the announcement of the “hit for explosives” Amanda Stanton Zug was not in the enhanced screening area. She was with the traditional x-ray. As she approached the enhanced screening area, she approached with the bin and the laptop of the person who was immediately in front of me in her hands. She took the IonScan swab running it over the computer. That person’s computer was not proximate to the still open H2O2 bottle. The sampling was performed in a different location,  removed from the proximate area of the open H2O2. She clamped the sampling wand of the 500DT with this person’s sample. That person’s IonScan ample did not alarm. Her computer was released.


The sampling wand of the Smith’s Detection IonScan 500DT

Next Ms. Zug returned to the traditional x-ray area to retrieve my bin that held my laptop. She placed the bin and my computer on the steel desktop where the already opened and recently VOC emitting Item #2 was or had only shortly been removed. She did not clean the steel table after Item #2 was there. She did not run a blank after the alarm. Of course, a non-alarm sample test is not a blank. Without changing gloves, without cleaning the sampling site or doing anything to determine residual VOCs present from Item #2, she wiped down my laptop. She inserted it in the wand. Not surprisingly it alarmed.

Ms. Zug announced a hit for explosives. A supervisor was summoned for a pat down. I immediately protested. I asked for a re-scan, but only after the manufacturer’s contamination protocol was followed. I asked what it was an alarm for. I was told that they could not tell me. They then removed all items from the steel desk including the offending Item #2 and sprayed it down.

Then entered Supervisor Shawn Knaub who was previously present in the area. This is when the video begins documenting the events up to the enhanced pat down.

There are many issues to consider in this video:

  1. Amanda Zug announces: “I am not ETD. I am only AIT.” The ETD is explained above. AIT is an acronym used by the TSA for a job description known as “Advanced Imaging Technology” which is the millimeter backscatter operator. By implication of her declaration, it can be deduced that she is not certified on the ETD (the IMS based IonScan device). As any scientist knows (and also according to good old fashioned common sense) a valid result can only come about on a stable instrument, using a validated method that is adhered to, using relevant traceable standards, and by an operator who is trained appropriately on the device. Manager Shawn Knaub should have known that his supervisee was not ETD trained. Supervisor Shawn Knaub should have known the moment that she made this declaration and properly refused to do the additional screening that he did not have a valid and reliable alarm from her analysis and should have realized that his analysis (the no alarm test conducted after the contamination protocol was performed) was the reliable and valid result. This should have halted the invasive search and pat down. It should have been resolved with a simple apology. [At the time I did not know what the acronyms ETD and AIT stood for.]
  2. Supervisor Shawn Knaub checking that the verific was in order. I appreciate that. Not allowing me to evaluate it is not. His not examining the full plasmagram is not appropriate. FOIA will tell us if there was in deed a verific valid for that day with a preserved plasmagram.verificpen

    An example Verific sample report


    An example Verific sample report page 2


    An example Verific Plasmagram

  3. Amanda Zug agrees that she did not clean the testing site after the initial and subsequent alarms from Item #2, prior to testing my device. This is against the manufacturer’s protocol.
  4. The swab holder was not cleaned with alcohol. The Velcro pad was not replaced. No blank was performed after an alarm was run. No “Cleardown” was performed as required by the manufacturer. A blank is never another sample. This is against the manufacturer’s protocol.

    Smith’s Detection IonScan Operational Manual


    Smith’s Detection IonScan Operational Manual

  5. No blank was run between samples. Again an unknown can never be a blank. This is against the manufacturer’s protocol.sampleanalysis
  6. As a matter of my opinion (and I suspect a lot of citizens), Supervisor Shawn Knaub asking me “Is this [being respectful, recording the TSA, and simply asking questions] part of your protocol? Is this part of the protocol for your company?” was inappropriate and bordering disrespectful.
  7. The claim that the screening protocol is not accessible to those who are subject to enhanced and very personal searches is unacceptable. While I appreciate that there is a balance between security and public information, I openly wonder if it is indeed part of their published protocol (if one exists):
  • to not control the site of examination and where samples are to be tested,
  • after an alarm happens to not cleanse the site,
  • after an alarm happens to not run a blank,
  • after an alarm happens to not seek a background reading of the area to make sure there is no lingering contamination,
  • after an alarm happens to not change gloves of the operators or those who were in the site of examination,
  • to allow untrained and not certified operators to run devices,
  • to totally disregard a no-alarm result after the contamination protocol is followed from someone who is in fact presumptively a certified operator,
  • to credit an invalid result over two valid results, and
  • subject a citizen to non-scientifically derived conclusions that are consistent with those trying to harm others and conduct a totally evasive search of all belongings and of my most intimate areas (but I guess if it is with the back of the hand).

I edited the video to not include the humiliating and very evasive enhanced pat down that I had to endure because no one either knows or follows the manufacturer’s protocol. I will keep that video for my own. I may publish it later. I may not.

After the pat down I was given an expired personal property/personal injury from Manager Bradley Kendall:

Personal Injury-Property Loss Form

Note that it reads that it expired 11/30/2011.

Expiration notice

Later I learned that Alex’s offending Item #2 was released to him. He got to his destination. I did as well.


On balance, I openly wonder about the technical qualifications of Ms. Zug when she writes on her Facebook:


Amanda Zug

Zug status update

On balance, given his comments to me and given the below Facebook post, I wonder if Supervisor Shawn Knaub has the sufficient lack of bias needed to be in his position:

Supervisor Shawn Knaub

Supervisor Steven Knaub

Knab post

He is entitled to his own opinion and freedom of expression


Here is what I have sent TSA:

• A completed SF-95 claim that was faxed
• A preservation letter for the ESI and data for the incident
• A FIOA request for:
⁃ the security screening protocol in place on that day,
⁃ the verific data for that day
⁃ the ESI data for the device used
⁃ time cards or their functional equivalent for all TSA employees present on that day
⁃ the video of the screening area for that time
⁃ the training certificates for the Smith’s Detection IonScan device for Amanda Zug
⁃ all forms of training certificates for Amanda Zug
⁃ the training certificates for the Smith’s Detection IonScan device for Steven Knaub
⁃ all forms of training certificates for Steven Knaub


My Root cause analysis:

Is this the manufacturer’s fault? No.

Is it the instrument’s fault? No.

Is it TSA’s fault? Perhaps. Better education is clearly needed. Better safeguards need to be put in place to only allow people who are certified on an instrument to operate the instrument and have the results justify an enhanced pat down.

Is it Amanda Zug’s fault? Yes. She should not be operating equipment that she has not been certified on. She knowingly did so. This is wrong.

Is it Supervisor Knaub’s fault? Yes. This is a classic failure to supervise. There appears to be little monitoring of people and what they are or are not qualified to do. There also appears to be a lax culture where co-workers allowed Zug to operate an instrument when she should not. He should have known the qualifications of his supervisees. He should have immediately realized by Zug says “I’m not ETD. I’m only AIT” that he had an invalid alarm generated by an untrained operator. Further, he was present when I got her to confirm that she did not spray down the area after the other alarm and followed none of the contamination protocols. This all coupled with his negative result after the contamination protocol was followed should have resulted in an apology to me for the inconvenience and a discharge from further screening.

Is it Manager Kendall‘s fault? Yes. Although he showed up to the seen after Zug made all of her admissions, he should have pressed his supervisees to verify what the recording and what their own admissions mean. He should not have given me an expired and not topical complaint form.

Who’s fault it isn’t? Mine and other law abiding citizens like me across this country.

My conclusion of the matter

While some people will just simply think to themselves “Jeez Justin just suck it up. Better safe than sorry.” I cannot. I will not. I was personally touched in a manner that I did not want, was not justified and was based upon a falsehood.

Maybe some simpletons will call me unpatriotic. But the security of us all requires diligence and valid testing. Understanding limitations and what results means will not simply result in greater efficiency with fewer false positives but also greater safety through lower rates of potentially calamitous false negatives.

A TSA agents job has to be tough. It has to be filled with stress. I could not imagine what it would be like if someone get through their screening area with a weapon or explosive device and it harmed others. That must be a tough reality of possibility to carry day in and day out. If you couple that with people who are over-stressed and in a hurry to get to their destination, it is perhaps a formula for mistakes. Mistakes do happen. Multiple and repeated mistakes and known errors cannot be simply dismissed or glossed over when it comes to transportation security.

Perhaps what alarms me most as a citizen is the lack of proper protocol awareness (or perhaps they are aware and just did not adhere). The manufacturers continue to make these devices so dangerously simplified so that fast is better than valid. False positives happen all the time. The goal should not be “IMS… so simple even a caveman can do it” but instead make sure

It is hoped that this blog will inspire Ms. Zug and Mr. Knaub to obtain better training and seek to better understand the meaning of the results that they get. It is one thing to have a readable result. It is a whole other thing to have a valid result.


Also, I wanted to be fair. I wanted to provide all 3 TSA agents (Knaub, Zug and Kendall) an opportunity for fair reply and/or a confession of error. I published this post as private requiring a password (meaning not linked to the blog, and not publicly searchable from search engines or through the search feature of the blog) but nevertheless once the url is provided they could see and read the entire post (including this end note). Here is what I wrote each of them on their FaceBook.

Dear (insert name),

My name is Justin McShane. I am the citizen that you encountered this morning (12/17/2014) at about 0520 to 0615 hours. I have published a blog post and published the video that I took. I encourage you to view it. It can be discovered only by people with the url. The url is http://wp.me/p5spZl-2J3. The password is “TSA.” I published this post as private (meaning not linked to the blog, and not publicly searchable from search engines or through the search feature of the blog) but nevertheless once the url is provided you can see and read the entire post as it will appear. In the post it catalogs errors that occurred this day, the manufacturer information and documentation as to the errors, and a root cause analysis. I want to be fair. I hold no ill will. I think this case study provides for a rich teachable moment for many. Unfortunately, it was at my expense. I am happy to publish any written response or any information that you care to share with me and my readers. I will not edit your comments. I think it is reasonable to put a 48 hour limit to any fair reply or confession of error. Therefore, this post will publish with or without your comments on December 19. I look forward to receiving your reply. Thank you. Justin McShane


Facebook Message sent to Steven Knaub offering an opportunity to reply prior to publication


Facebook Message sent to Amanda Zug offering an opportunity to reply prior to publication

Blog update 12/19: There has been no reply. Therefore the blog has been published.

We have blogged on here a lot about the need for forensic science reform and how the current state of forensic science with no meaningful oversight is not unlike the Wild Wild West.

Consider this reporting from CNN. If these claims of CNN turn out to be true, it is just amazing. Perhaps we have found a new poster child for forensic reform? And if true, it serves as a stark reminder to check the credentials on everyone.

Shawn Parcells in the white shirt

Is ‘professor’ who helped with Michael Brown autopsy who he says he is?

By Elizabeth Cohen and Matthew Stucker, CNN
updated 12:02 PM EST, Thu November 27, 2014

(CNN) — The last thing an attorney might expect to receive at a deposition is a brain, but that’s what the man said he was handing over.

A brain. In a bucket.

Sliding the bucket across the table and opening the lid, the man urged the lawyer, Michael Hodges, to take it. Hodges declined. The deposition continued.

This might have gone down as just on odd moment in Kansas legal history were it not for the fact that about a year later the defendant, Shawn Parcells, ended up playing an instrumental role in the case of Michael Brown, who was fatally shot by a Ferguson, Missouri, police officer in August.

Parcells became an overnight media star in August when he assisted in an autopsy commissioned by Brown’s family. He appeared time and again on major media outlets as a forensic pathology expert. He said over the years he’s testified in court dozens of times in several states.

But an investigation by CNN that included interviews with attorneys, law enforcement and physicians suggests Parcells isn’t the expert he seems to be.

And handing a lawyer a brain in a bucket isn’t the only unusual thing he’s done.

No signature — and a suspect set free

In 2012, Parcells Regional Forensic Services was hired by Andrew County, Missouri, to do an autopsy on Robert Forrester, 74, who doctors said died of a brain bleed. Police suspected manslaughter.

Two days before Forrester’s death, he told officers that his grandson Bobby Forrester, 23, had hit him in the face and “knocked me the f*** out.”

Parcells told CNN he performed the autopsy on Forrester without a doctor present.

On the first page of the autopsy report, it states that “this final autopsy report has been reviewed and signed by:” and then underneath there are lines for signatures for Edward R. Friedlander, M.D., a pathologist, and for Parcells.

According to the sheriff’s incident report, the county coroner “advised he was contacted by a doctor who advised he did not see this autopsy or sign the report as it was showing he did.”

Friedlander declined to discuss the case with CNN.

Parcells said he listed Friedlander by mistake on the first page of the report, and the autopsy report was actually done by Dr. George Vandermark, whose name appears on the next page — but Vandermark tells CNN he had nothing to do with Forrester’s autopsy.

The report was never signed.According to the county, without a valid autopsy report signed by a doctor, a cause of death can’t be officially determined and no one can be prosecuted.

Police took Bobby Forrester, who has a history of psychiatric illness, to a hospital for a four-day mental health evaluation. After testing, Bobby Forrester was released from the hospital.

Nine months later, Forrester assaulted his grandmother, who was found lying on the floor bleeding with two swollen black eyes. He’s now serving a four-year sentence for assault.

Parcells insists that the Robert Forrester death investigation was “doomed from the start” because the dead man’s body was embalmed prior to the autopsy, and because the sheriff’s department never turned over records needed for the autopsy report to be completed.

The sheriff’s office says Parcells never asked for such records.

Who is Shawn Parcells?

Parcells, a Kansas native, says he became interested in death at age 12 when his grandfather passed away.

“I actually started doing autopsies my junior year in high school,” he said. “I’ve been doing this a long time. I love it.”

Right after high school, renowned pathologist Michael Baden made a visit to Kansas. Parcells snapped a photo with him.

By college, Parcells said, he was teaching first-year residents how to do autopsies. The campus newspaper, The Kansas State Collegian, wrote an article about him in 1999 headlined “Morbid Curiosity.”

He received a bachelor’s degree in life sciences from Kansas State in 2003, and he said he was immediately accepted to medical school in the Caribbean, but his wife got pregnant and he wanted her to receive her care in the United States, so he didn’t attend.

Earlier this year, Parcells’ LinkedIn page said he expected to start medical school at the International University of the Health Sciences in the Caribbean starting in September 2014. Later, the date was changed to 2015.

When CNN visited Parcells in his Overland Park, Kansas, home, he presented a photo of himself onstage at what appears to be a graduation ceremony at the New York Chiropractic College.

“I got a master’s degree in anatomy and physiology, with clinical correlation,” he said.

Asked where his diploma was, he replied that it was on the way. “It’s coming,” he said. “They mail it to you.”

The next day, at another on-camera interview, the conversation went like this:

CNN: So that master’s degree in New York, you have that degree?

Parcells: I will have it next month, yes.

CNN: I don’t mean the piece of paper. I mean have you been conferred that degree?

Parcells: Yes, I will. Next month.

CNN: Right now, as we speak, you have that degree?

Parcells: No, I do not.

Parcells doesn’t claim to have any specific license or certification to do the work he does. He knows how to do autopsies from “on-the-job training,” watching pathologists and assisting them at various morgues, he said. Sometimes he’s been paid for this work and sometimes he wasn’t, he added.

“To take out organs and to cut open a body, you don’t need to be a pathologist,” he said. “Come to an autopsy. I think when you see what I do, you’ll realize that I’m not just making this stuff up out of blue, thin air.”

He certainly sounded knowledgeable and authoritative on August 18 when he presented the findings of the Michael Brown autopsy to a nationally televised news conference.

Baden, who conducted the autopsy, spoke first, and then introduced Parcells, saying he “has been instrumental in the autopsy evaluation.”

“First of all, I’m Professor Shawn Parcells,” Parcells said as he stood to address the reporters.

On his LinkedIn page and to CNN, Parcells said he’s an adjunct professor at Washburn University in Topeka, Kansas — but a spokeswoman for the university told CNN that’s not true.

“(Parcells) is not now and has never been a member of the Washburn University faculty,” university spokeswoman Michaela Saunders wrote in an email to CNN, adding that at one point, Parcells spoke without receiving pay to two groups of nursing students about the role of a pathologist’s assistant and gave a PowerPoint presentation and answered students’ questions.

‘If they want to think I’m a doctor, that’s their issue’

Parcells says he sometimes performs autopsy procedures without a physician present, and that’s legal as long as he’s under a doctor’s supervision and the doctor signs off on the report.

“I’m not coming up with the cause of death, and I’m not making the final diagnosis,” he said.

At the same time that Parcells was doing autopsy procedures without a doctor, his company was distributing a letter saying he never did that.

A March 5, 2012, letter addressed “To Whom It May Concern” outlines “myths” and “facts” about his company’s practices.

“MYTH: Our pathologists are never or seldom present during an autopsy examination.

“FACT: During each and every forensic autopsy conducted, the attending pathologist is present at all times … WE ALWAYS HAVE THE ATTENDING PATHOLOGIST PRESENT AND DIRECTING THE AUTOPSY EXAMINATION.”

Parcells told CNN that even though it’s on his company’s letterhead, a physician he worked with, and not him, wrote the letter, which is unsigned.

Laws in Missouri and Kansas aren’t completely clear on whether it’s legal for someone who’s not a doctor to perform an autopsy procedure without a doctor present, but one thing is clear: Some coroners and law enforcement agencies aren’t happy about what Parcells is doing.

Grant Gillett, a deputy sheriff in Andrew County, Missouri, said Parcells told them he was a doctor — a pathologist specifically — when he walked into the funeral home to do the Forrester autopsy.

Dustin Jeffers, who was also a deputy at the time, said Parcells identified himself as a doctor. The Andrew County Sheriff’s Office incident report refers to him as “Pathologist Shawn Parcells” and “Dr. Shawn Parcells Pathologist.”

Parcells says he never told the deputies he was a doctor.

“If they want to think I’m a doctor, that’s their issue,” Parcells told CNN. “People assume stuff all the time. And they may never ask. It’s bad that they’re assuming and that they never asked. If they want to think I’m a physician, then more power to them.”

Officials in another county in Missouri filed a complaint with the Missouri Board of Registration for the Healing Arts when they found out Parcells “conducted (an) autopsy with no pathologist present.” The board reviewed the complaint about the 2011 autopsy and voted to close the case.

Pathologists interviewed by CNN say they’re concerned that a man who has no formal education in pathology is giving testimony in court that could possibly help put innocent people in jail or let guilty people go free.

“I would certainly say questions should be raised about any case in which he has a part,” said Mary Case, the chief medical examiner for St. Louis County.

As for the case where an attorney was handed a brain in a bucket, a Kansas widow who wanted to know the cause of her husband’s dementia sued Parcells after he told her he would remove her husband’s brain from his body and send it to Harvard Medical School for analysis.

The widow, Judy Walker, said she paid Parcells $1,250 in 2011 but never received a report from Harvard. Her lawyer, Michael Hodges, said about three years later — after the lawsuit was filed — she received a report from a doctor in New York.

Hodges said he’s not sure if the brain in the bucket belongs to Walker’s late husband, Michael Doris, or if it’s even a brain at all.

“Plaintiff now believes that her husband’s brain has been lost or destroyed,” according to the complaint.

Parcells says that’s why he brought Walker’s late husband’s brain to the deposition. And if she ever wants it, he says, it’s in his lab in Topeka, safe and secure.


What is a Tune Report and Why is it important in GC-MS work?

Would Eric Clapton ever play a concert or for a recording on an out-of-tune guitar? Of course not.

The tune on a GC-MS instrument is as important if not more than the tune on Eric Clapton’s guitar. When the result matters, Clapton makes sure that his guitar is in tune prior to preforming so that he has confidence that the result of his using his instrument. When the results matter in a criminal case (which is in every case), and a GC-MS instrument is used, the GC-MS instrument must likewise be proven to be in tune or the results may be compromised.


We have written on this blog a lot about the Gas Chromatography with Mass Spectrometer instrument because it truly is the workhorse in forensic science. You can see our main post on how it works here:

How does a GC-MS machine know that there’s a drug in the blood or urine?

And we have an entire category devoted to this great piece of technology here:

GC-MS posts

In all sincerity I state emphatically that is one great instrument. When I write about GC-MS, I am referring to the classic single quadrupole device. I think it is just scientifically the cat’s pajamas. In fact, in a laboratory, the GC-MS device and the LC-MS-MS are by far my favorite devices to operate, maintain, and run. When the 5 Q’s [i.e., Design Qualification (DQ), Installation Qualification (IQ), Operational Qualification (OQ), scheduled repeat OQ, Performance Qualification (PQ), and Re-Qualification after Repair (RQ). See more about the 5 Q’s in this post “A Forensic Measurement Device is Not an X Box”] of putting a GC-MS into service are followed, it can be a very powerful device of discovery. There is a reason it has earned its reputation as “the gold standard.” Sadly, not many Quality Assurance Managers or Quality Risk Management (QRM) officers in forensic laboratories have ever heard about the 5 Q’s. True equipment qualification, which is required in the pharmaceutical field, is lacking in all but a few laboratories in forensic science.

So, in a GC-MS context with or without adherence to the 5 Q’s, how can we all be sure that we have good quality results?

The sad truth is without adherence to the 5 Q’s, you may not have a valid result… ever.

One of the 5 Q’s is PQ or Performance Qualification.PQ refers to the test or validation protocol carried out by the user, offering documentary evidence that the instrument is maintaining the agreed values.

In the GC-MS world, a big part of any sort of validated instructions (sometimes called Standard Operating Procedures or SOPs) is the tune of the Mass Spectrometer.

Is the tune and the tune report evidence that the system is working well and will develop valid results every time?

No. The tune of the MS is a check of the MS system only. It is vital to note that if an instrument passes the tune and is functional, it does not mean the the Gas Chromatograph is working appropriately. The tune compound is directly injected into the MS and does not go through the GC system at all. While a tune is important, it is one part out of many that concerns quality control (QC). Proper QC is only a small part of what comprises a valid result.

What is a tune and why is it important to tune the MS? Why do we need to perform a tune on the MS?

The power of the GC-MS system is its multiple points of information that it gathers. From the GC, we get the retention time. From the MS we get ions and a spectrum. The key to the qualitative identification is in the ability to take the retention time, and combine it with the fragmentation pattern that results in the spectrum and compare it against a library of results from Certified Reference Materials that have been tested on that instrument in that environment to come up with some metric of similarity, whether it be a match factor, quality score, probability score or something similar. As this is a function of comparison between a standard and an unknown, the key then is in the reproducibility of the results. If the results are not reproducible, then the computerized library qualitative identification may be wrong or the metric used to determine similarity will be skewed. So this is why we need a means to assure that the fragmentation pattern is performing as it should. We use a compound, usually PFTBA (perfluorotributyl-amine), that is directly injected into the MS device. PFTBA is almost the universal choice in tune compounds because it is a very stable compound with a very well known and uniform fragmentation pattern. It also has masses that clearly fragment at low, medium and high ranges.

PFTBA container that is directly injected into the MS

A comprehensive tune of the MS evaluates the RF/DC frequency at several masses, relative abundances, isotopic ratios, the Electron Multiplier voltage, various temperatures and pressures as well as for leaks in the system. If needed it refocuses the lens or makes adjustments in these variables to tune it correctly so that the results are reproducible. At the end of the tune, a tune report and maybe a tune evaluation is printed out. These tune reports and evaluations must be kept to prove adherence to the QC protocol and tracked over time to evaluate changes in the system.

How frequently should a tune be performed?

When results matter and critical decisions are made, the QC system has to be comprehensive and frequent. A frequent QC regimen that is robust reduces the risk of being wrong.

A good guide into best practices for MS work can be found in “Best Practice Guide for Generating Mass Spctra” by Vicki Barwick, John Langley, Tony Mallet, Bridget Stein, and Ken Webb. This was a consensus document produced by mass spectrometers that are part of the UK’s Department of Trade and Industry’s VAM Programme which forms part of the UK National Measurement System. According to the authors:

The Guide arose from discussions held at the VAM Mass Spectrometry Working Group and was prepared by LGC in collaboration with the members. In addition to major contributions by the authors, other member s of the Working Group provided suggestions and comments. The idea for this work came about during preparation of an earlier guidance document concerning accurate mass (“AccMass”) applications of mass spectrometry. It became clear that users of mass spectrometry instrumentation or services, including both specialists and research chemists, frequently have little understanding of the instrumentation or the meaning of the spectra they produce. Often, they will obtain or request an accurate mass determination for confirmation of identity on the basis of spectra which are meaningless or which could not possibly have originated from the target molecule. Discussion of this problem highlighted the changes which have taken place in teaching chemistry and analytical science and the rapid expansion in the application of mass spectrometry. The latter has been fueled by a number of factors, including advances in the automation and performance of instrumentation and recent rapid growth in the use of mass spectrometry for the biosciences. The outcome has been widespread use of complex instrumentation, often as a “walk up” service, by staff with little education or training relevant to the task. The main aim of the Guide is to enable those unfamiliar with mass spectrometry to generate mass spectra that are fit for purpose, primarily for qualitative analysis of small molecules. We have done this by providing a clear and concise summary of the essential steps in obtaining reliable spectra.

Later in the Guide, we find the following outline of the essential steps in obtaining reliable spectra:

5.1 General sequence

• The general sequence of actions when acquiring a mass spectrum is as follows: tune instrument, mass calibrate, acquire a background spectrum, analyse a test compound, analyse the sample. This sequence requires a number of essential checks on aspects of instrument performance before acquiring a mass spectrum, to ensure that spectra obtained for samples will be of acceptable quality. Initial instrument performance should be checked by acquiring the mass spectrum of a test compound using a defined protocol.

So in short, a tune must be performed (along with other aspects of QC) every single time before a batch is run. Best practices dictate a bracketed approach whereby a tune is run before a batch and then after. We evaluate the two tunes and look for meaningful differences. If there are none, then we can infer that the instrument was in tune during the batch testing. If there are meaningful differences, then we can infer that there may have been an error during the analysis and the validity of all results are compromised.

The laboratory says that it did a tune, is that good enough?

Not all tunes are alike. There are three major types: (1) Quicktune, (2) Autotune, and (3) Standard tune. A Quicktune only examines the Electron Multiplier and the peak width. No lens corrections are made. It can be thought of as an act of verification, not a true robust tune. A Standard tune does all of the acts that the Quicktune does, but it adds in standard response values over the mass range. The Autotune performs a total system verification and adjustment if needed. It is the most comprehensive of the three. It is the autotune that should be performed and evaluated every day as well as evaluated over time. And even beyond the simple fact that a tune was performed, is the major question of is this particular tune any good? Unlike courthouse and courtroom folklore, the MS will operate if it is out of tune. A good number of GC-MS operators that I have encountered have no idea how to interpret an autotune report or know what acceptable values are.
In conclusion, don’t let your crime laboratory be like this guy:

and have them try to tell your jury that it is like Eric Clapton and/or Kirk Hammett and/or some really talented guitar player who is in tune.

Tuning matters.


Like Bill Clinton’s famous re-framing of the issue in this video:

It depends on what your definition of “positive” is? TLC in marijuana testing

We have posted here before about the Thorton-Nakumura protocol that is used throughout the United States for the prosecution of illegal possession of marijuana (in its solid drug dose pre-consumption form). A fair examination of the question reveals that there is no validity to the notion that the 3 test regimen produces a valid conclusion that the unknown examined in fact contains THC. Here are those posts:

Here are those series of posts:

  1. What is the goal and the purpose of testing of unknowns generally? How do we best design a test for marijuana?
  2. How is most marijuana testing conducted in the United States?
  3. What is microscopic morphological examination? Is it a “good” test?
  4. What is the modified Duquenois-Levine test? Is it a “good” test?
  5. What is Thin Layer Chromatography? Is it a “good” test?
  6. Is the combination of all three tests create a “good” testing scheme?
  7. Is there a better way to test for marijuana?

We looked at great detail about Thin Layer Chromatography in Marijuana testing in the following post What is Thin Layer Chromatography? Is it a “good” test?

There are also may publications that describe known false positives such as coffee, tobacco and basil.

Beyond that, the test to a large degree is totally subjective in its interpretation. Case in point consider this TLC plate:


Is this a positive

Is the sample labelled B2 a positive?

Different people can answer this differently, I suppose.

But what makes it worse is that few if any laboratories preserve their plates or take pictures of the results. So what you are left with is an unverified subjective opinion of someone who is in an adversarial position from the accused with no data that will support the “positive” call by the analyst. Doesn’t seem very scientific to me.

It’s time for SWGDRUG and drug seizure laboratories to come out of the 1950s and the 1960s and get with modern objective and valid science. It’s time to stop the non-validated Thorton-Nakumura protocol and move to GC-MS (it’s not that hard just put it in a methanol suspension and shoot away) and another technique Category A or Category B to verify it. Is it really that hard to do?