Corruption: Forensic Misuse of DNA 

in the Labs and Courtrooms

Part 1. Las Cruces, New Mexico: Collapse of the Forensic Testing Laboratory

          Stefan Long was the General Manager of a fledgling forensic biology/DNA lab, established on the campus of New Mexico State University, in Las Cruces, New Mexico. The Forensic Testing Laboratory (FTL) hired Dr. Michael Spence to assist with achieving accreditation. FTL sought to become a productive outsource analytical facility, offering DNA testing services for criminal casework. In addition to his salary, Dr. Spence was under contract to earn 4% ownership of the FTL enterprise—upon accreditation of a successfully functioning outsource lab. In June of 2007, Spence began his work efforts—pursuing FTL’s accreditation objective.

Near the end of the workday, on Friday, August 17, 2007, Dr. Spence was asked by numerous scientific co-workers, to attend an FTL employee gathering—to discuss concerns with Mr. Long’s faulty approach to lab management. In attendance: Dr. Spence, Ms. CS,   Mr. DS, Ms. HO, Mr. MT, Ms. NG, and Ms. DS. At the meeting, Dr. Spence was confronted with a disturbing inventory of Stefan Long’s reported managerial indiscretions. Since Spence had only been with FTL for two months, and with no significant personal objections regarding Mr. Long’s approach to leadership, he was only moderately alarmed. However, his neutrality rapidly deteriorated when all of the scientists in attendance voiced their indignation over how Stefan Long typically ‘disciplined’ those individuals who found themselves in Steve’s doghouse. Dr. Spence was overwhelmed by the unanimous accounts, that Stefan Long routinely tampered with the scientific work—of any individual who dared to question his authority. Among the attendees, it was also agreed that Mr. Long would subsequently censure the scientist for their failed results. Upon learning of such abominations, Dr. Spence, understandably, ...was horrified. Spence assured his co-workers that such treachery would not be tolerated in the accredited DNA lab. After all, FTL’s goal was to process DNA from cases involving homicides, sexual assaults, armed robberies, fatal accidents, and a myriad of other serious matters.

Tragically, Dr. Spence had not yet realized his lack of influence over the specifics of the FTL lab’s eventual day-to-day security functions. Months after that informal August meeting, Spence found himself at odds with Stefan Long—regarding the most fundamental issues. Dr. Spence was insisting that—within FTL’s accreditation documents—there needed to be guarantees that no access would ever be allowed into the critical FTL casework areas, with the exception of working scientists who possessed the required certification. Since Stefan Long had no plans of pursuing qualifications as a forensic analyst, this would prevent his continued 24/7 access through the coded doors, into any of the restricted analytical areas. Mr. Long vehemently disagreed with Dr. Spence on the topic of incorporating such safeguards into the FTL Quality Assurance documents. Stefan Long, as the self-appointed FTL Quality Assurance Manager, insisted upon his 100% unregulated access to those critical analytical sections within the facility—at any time, ...day or night.

In late January of 2008, as Dr. Spence attempted to validate a fundamental DNA processing step required for FTL accreditation, it became clear that Mr. Long was tampering with those efforts. On February 7, 2008, the inevitable confrontation ensued between Dr. Spence and Stefan Long. Spence had reached the end of his tolerance for Long’s bullying tactics—particularly the juvenile tampering with the work efforts of any scientist in Steve’s doghouse. Dr. Spence hung up the phone on Mr. Long, and promptly gathered his personal belongings. When Dr. Spence hung up on the tyrant a second time, Mr. Long walked to Spence’s office and demanded that he remain within the facility—until the exit interview could be completed.  

During that exit interview, Stefan Long’s abrasive antics deteriorated to a level at which Dr. Spence had no choice but to call 9-1-1 law enforcement dispatch. This was in order to ensure his safe exit from Mr. Long’s bullying. In the midst of all of these histrionics, Stefan Long memorialized his version of the events—within his “Memorandum for Record”—signed: “Stefan A. Long”. The subject line of that document accurately characterized Dr. Spence’s departure as a: “Resignation”. Throughout the many years that followed, Dr. Spence preserved this document, in anticipation that Stefan Long would inaccurately claim that a “firing” had occurred.

Aligned with that anticipated nonsense, on Friday, February 8, 2008—the very next day after Dr. Spence executed his escape from FTL—Stefan Long placed a phone call to the Indiana State Police Regional Crime Lab, in Evansville, Indiana. Long spoke to Dr. Spence’s former employer, Sergeant Joseph Vetter, the Manager of the ISP Evansville facility. In contradiction to Stefan Long’s “Memorandum for Record—Resignation”, from less than 24 hours earlier, he lied to Sergeant Vetter. He alleged that Dr. Spence had become hostile, had to be fired, and forcibly removed from the facility by the NMSU Campus Police. Mr. Long also informed Sergeant Vetter that Dr. Spence brought his 11-year-old son into a restricted lab area, and abandoned him there for a protracted time frame. 

Unfortunately, Stefan Long took this vindictive, ‘poisoning-the-well’ crusade one step too far. When Long fabricated the tall tale that official “ISP case documents, evidence samples, and other stuff”, had been discovered in Dr. Spence’s desk at FTL, the ISP response was predictable. ISP leaders instructed Sergeant Vetter to immediately book travel arrangements to Las Cruces—to recover all of the ridiculously alleged documents/evidence that might have been illicitly removed from the ISP-Evansville Crime Lab.

In an April 6, 2009, email reply from Sergeant Vetter-to-Dr. Spence, Vetter summarized his February 2008 visit to FTL: “...I went to New Mexico in order to determine if you might possibly have materials that belonged to us and not you.” Sergeant Vetter continued with: “...we examined all of your materials and determined that you had a perfect right to have what you had.” Thus, on February 13, 2008, Vetter made the 1400-mile journey. Shortly after his arrival, the man realized that his time had been completely wasted, ........along with 1000’s of Indiana taxpayer dollars. This was all due to Mr. Stefan Long—and his oppressive penchant for tampering.

Recall that—on Friday, August 17, 2007—Dr. Spence was first informed of Stefan Long’s treacherous behavior, including tampering with scientific materials. One of the people attending that Friday evening meeting of co-workers was Ms. CS, a scientist who worked closely with Dr. Spence—throughout his 8-month tenure. One week after Dr. Spence managed his escape from Mr. Long’s tyranny, Ms. CS issued her resignation notice—for remarkably similar justifications. Since March of 2008, Ms. CS has successfully worked as a forensic DNA analyst, within a Texas crime lab located 57 miles outside the clutches of Stefan Long/FTL.

Shortly after the 2008 departures of Dr. Spence and Ms. CS from FTL, a meeting was arranged between Spence and the Undersheriff for the Doña Ana County Sheriff’s Department. During this meeting, Dr. Spence voiced a detailed inventory of justifications for why local law enforcement investigators should exercise extreme caution, before considering Stefan Long/FTL for outsource DNA analytical services on criminal case evidence. This included descriptions of the toxic work environment, the tampering with scientific materials, and the false account of facts that Stefan Long voiced to Sergeant Vetter, with the ISP Evansville Crime Lab. Interestingly, in 2008, the Doña Ana County Undersheriff was Mr. Chuck Franco. Three years later, Chuck Franco began serving as the First Gentleman of New Mexico, with his spouse, Governor Susana Martinez. Martinez served as the leader of the state of New Mexico for two terms—spanning from 2011 through 2019.

Five and ½ months after Dr. Spence resigned from FTL, Mr. Long launched yet another attempt at tampering with Dr. Spence’s professional reputation and livelihood. On July 24, 2008, two NMSU Campus Police detectives unexpectedly arrived at the office of Spence Forensic Resources. Mr. Long had filed a ludicrous, falsified Crime/Incident Report with the NMSU Police. In that report, Stefan Long alleged—yet again—that “Dr. Spence was fired in February.” He claimed—yet again—that Dr. Spence “...became argumentative...” on that day, and “...had to be removed from the building.” Defying all sense of logic, Long also alleged that Dr. Spence committed larceny, by stealing a USB key card that was essential for operating a genetic analysis software program. Astonishingly parallel with the nonsense that Stefan Long tried to feed Sergeant Vetter—on February 8, 2008—he attempted a renewed tampering effort—by filing the false law enforcement report. Subsequent to this criminal activity—perpetrated by Long—Dr. Spence submitted three emails to the NMSU police. These messages were dated August 22, 2008, September 5, 2008, and September 12, 2008. These emails addressed the NMSU Campus Police Investigator, Lyn Hodges, as well as the NMSU Chief of Police, Steve Lopez. Dr. Spence implored these investigative authorities to thoroughly complete their dissection of Stefan Long’s libelous delusions. Furthermore, he emphasized that—in the inevitable event of zero findings—there needed to be an investigation into Mr. Long’s violation of law—filing a false police report. In those emails, Dr. Spence unequivocally predicted that this miscreant would continue his ill-conceived attacks—targeting the reputation of a successful DNA scientist. Through all of the years beyond Long’s bizarre larceny allegation, Dr. Spence has received no updates on this matter—from anyone within the NMSU Campus Police.

In January 2009, the FTL DNA testing facility finally achieved accreditation. During the 1½ years after Spence’s exit from FTL, Mr. Long managed to alienate four more Technical Managers. These events should lead one to ask the question: “Did an FTL-analyzed forensic DNA case ever arrive on Dr. Spence’s desk at SFR?”

Refer to New Mexico v. Michael Burns. Cause Number: CR 2009-733. The case synopsis unfolded as follows: A female resident of Las Cruces, New Mexico, arrived at home and realized that her burglar alarm had been activated. As the woman telephoned 9-1-1 dispatch, she spotted a stranger walking down her street, and described him to the operator. The woman also noticed an open window, facing her backyard. A trash can had been positioned on her back porch, beneath the open window. The police located the stranger, Mr. Michael Burns, as he walked through the neighborhood. Upon questioning the man, the officers decided that he had little justification for “taking a stroll” in that location. When the police searched the immediate area, they found a pair of lime green gardening gloves that had been stuffed into a gap in a nearby rock wall. The officers put their suspect into the back of a squad car and transported him to the allegedly burglarized home. When the complaining witness came to her front door, an officer held up the lime green gloves and asked “Are these yours?” The woman asked the officer to hold that thought for a moment, and went to her back porch. She returned to the front door and told the officer, “Yes! My gardening gloves are missing, and they look exactly like those!”

          Michael Burns was placed under arrest. The Doña Ana County District Attorney’s office had developed a theory. They believed that Burns, a professional burglar, had gained access to the victim’s backyard. When he found the gloves on the porch, he put them on to avoid leaving fingerprints. Burns then moved the trash can to a nearby window and crawled into the home. As soon as the intruder realized that he had activated the alarm, he vacated the house. A number of minutes later, Burns allegedly hid the gloves a few blocks away within a rock wall, in hopes of avoiding any connection to the residential break-in.

          Months after his arrest, Mr. Michael Burns was subjected to a criminal trial. During the trial, the defense emphasized the fact that the gloves could have been tested for DNA—either to connect them to the defendant, or to clear him of the charges. The jury agreed that the lack of DNA testing was a troubling issue. However, they could not agree upon a verdict. A 2^nd trial was placed on the calendar.

Prior to the 2^nd trial, the Doña Ana County District Attorney’s Office contacted Stefan Long, and commissioned FTL to test the gloves for DNA. The defense lawyer—  Ms. Beth Hubbard-Bramblett—brought Dr. Spence onto the case, to examine the documentation. Imagine the indignation of the taxpayers, in light of the inflated cost of two trials, plus expensive DNA tests, as well as the cost of a defense DNA expert. All of this, in order to get to the bottom of a stolen pair of filthy gardening gloves.

The attending FTL analyst—Mr. JM—properly turned each glove inside-out and carefully collected cotton swab samples. These swabs targeted various inner surfaces that certainly should have rubbed against the ‘handling skin cells’ of the wearer. Recall that the average-sized person, from head-to-toe, sheds approximately 2 million skin cells—over the course of each minute. Interestingly, the gloves both revealed a pristine, single-source genetic profile, perfectly matching the known DNA profile from Michael Burns. Although Dr. Spence readily agreed to the DNA match with the defendant, something was terribly wrong with this scientific picture.

          The problem: Where was the DNA from the burglary victim—the owner of the lime green gloves? From each glove, the only genetic material was the pristine set of alleles, demonstrating an exact match to Michael Burns. Note that this was in spite of the victim’s testimony that, once she purchased the gloves, she used them quite frequently—throughout numerous months. While the gloves were heavily soiled from the abundance of heavy yard work, the woman adamantly testified that she had never washed them—not even once. Despite this fact, the evidentiary results did not reveal one single genetic marker from the female burglary victim who had purchased and used those gardening gloves. Mysteriously, the case investigation team was never directed by Stefan Long—or anyone else at FTL—to bother with collecting a known DNA reference standard from the owner of the gloves.

When the prosecution became aware that the defense would be questioning FTL’s DNA results, they promptly voiced their indignation to the Court. They argued as follows: Considering that Dr. Spence was a former employee at FTL—this fact dictated that there should be comprehensive coverage for the jurors—regarding all aspects of Dr. Spence’s problematic history with Stefan Long.

The Court would have nothing to do with such nonsense. The proceedings were directed to move forward with no component of the ‘personalities’ associated with FTL’s history. The DNA aspects of the Michael Burns case would be evaluated strictly on interpretation of the evidentiary data. Thus, the jurors were never advised of any friction between FTL, and the defense’s DNA expert. Similarly, the jurors were never advised of the egregious, juvenile activities perpetrated by Stefan Long, especially his relentless tampering with Dr. Spence’s reputation as a scientist.

As the 2^nd trial date approached, Dr. Spence encouraged defense counsel to file a subpoena, demanding the video footage from FTL’s analytical area, in order to scrutinize the timing and events—during analysis of those gloves. Opposing counsel responded, explaining that no such footage was available—due to the mystifying absence of a functional video surveillance system, during the time of the lab work. True to his history of misdeeds, Stefan Long masterminded the evidence tampering—the planting of DNA from Michael Burns, into the glove samples. The facts of this investigation/trial can be readily verified through examination of the testimony record from Cause Number: CR 2009-733. On May 25, 2012, Dr. Spence and Mr. Stefan A. Long each summarized their assessments of the DNA case for the trial jurors. The verdict for Michael Burns: Not Guilty—on all counts.

As a consequence of Stefan Long’s criminal behavior, spawning the seemingly improbable verdict for Michael Burns, word spread rapidly among countless law enforcement investigators and prosecutors throughout New Mexico—and beyond. FTL’s reputation was plagued with the stigma of a toxic work environment, and—of course—DNA evidence tampering. Inevitably, the FTL enterprise suffered a breathtaking collapse—and permanently closed its doors in August 2015. This was unfortunate, as the FTL facility was remarkably well-equipped, and staffed with extremely capable scientists.

It takes just one bad apple.

Posted by Michael J. Spence, Ph.D., on May 1, 2024.

 

LITIGATOR'S HANDBOOK OF FORENSIC MEDICINE, PSYCHIATRY AND PSYCHOLOGY

In June, 2023, Chapter 8: Forensic Use of DNA, was published, along with 27 other chapters, via Thomson-Reuters-WEST. The 3-volume reference set bears the title: “Litigator’s Handbook of Forensic Medicine, Psychiatry and Psychology”. See link:

https://store.legal.thomsonreuters.com/law-products/Forms---Topical/Litigators-Handbook-of-Forensic-Medicine-Psychiatry-and-Psychology-2023-ed/p/106919469

Among the other 27 excellent chapters, Chapter 6: The Forensic Autopsy, was authored by the worldwide recognized forensic pathologist, Dr. Werner U. Spitz. The 97-year old German-American authored the definitive book, within the field of forensic pathology, "Medicolegal Investigation of Death", for which the 1st Edition was released in 1993. Dr. Spitz is credited for his work on the assassinations of John F. Kennedy, and Dr. Martin Luther King Jr., the deaths of Mary Jo Kopechne, and JonBenet Ramsey, and the trials of Casey Anthony, Phil Spector, and O.J. Simpson.

Over the course of eight challenging years of work, the Chapter 8 authors, Michael J. Spence, Ph.D., and Demosthenes Lorandos, Ph.D., completed their work.  By November 2023, the initial printing of the 3-volume reference set was 100% sold out. In addition to ramping up publication of another round of this handbook, Thomson-Reuters-WEST is encouraging contributing authors to execute their chapter modifications/expansions for EDITION II of the reference set. This updated edition should be released sometime in the coming few years.

An EDITION II preview of Chapter 8: Forensic Use of DNA, is below:

The updated edition will expand this chapter from 55,000+ words, to over 70,000 words. One of the sections will be entitled: Treachery in our DNA labs: From incompetence to outright fraud. This section emphasizes how vital it is for us to recognize the ‘red flags’ associated with professional misconduct—at the hands of those occupying elevated positions of forensic DNA responsibility. In simpler terms, ...the forensic misuse of DNA. We have all seen such scenarios unfold, as follows:

·       Ms. Jacqueline Blake, Federal Bureau of Investigation

·       Ms. Sarah Blair, Orchid Cellmark

·       Mr. Fred Zain, West Virginia State Police/Bexar County, Texas

·       Mr. Stefan A. Long, working experiences described by Dr. Spence

·       Ms. Yvonne "Missy" Woods, Colorado Bureau of Investigation

·       Dr. Pamela Fish, Chicago Police Department/Illinois State Police

·       Ms. Joyce Gilchrist, Oklahoma City Police Department

One of the modified EDITION II, Chapter 8 sections will bear the title: Recent developments in the forensic use of DNA. In this section, detailed DNA case descriptions will include the following:

·       State of California v. Lukis Anderson

·       State of California v. Joseph DeAngelo

·       State of Vermont v. John Grega

·       State of Washington v. Clay Starbuck

·       State of Wisconsin v. Steven Avery and Brendan Dassey

·       State of Michigan v. Gary Leiterman

Please note that, in the coming months, a four-part series of articles will be posted here at DNA Technology and Our Criminal Justice System. The title of this series will be "Corruption: Forensic Misuse of DNA in the Labs and Courtrooms." The titles and dates of these articles are as follows: Part 1. "Las Cruces, New Mexico: Collapse of the Forensic Testing Laboratory" to be posted here in early May, 2024. Part 2. "NM-DPS Crime Lab: Misrepresentation of DNA Casework Contamination Errors" to be posted here in early June, 2024; Part 3. "Corruption in the El Paso County (Texas) District Attorney's Office" to be posted here in early July, 2024; Part 4. "Missy Woods: Forensic DNA Fraud in Colorado." to be posted in early August, 2024.

Posted by Michael J. Spence, Ph.D. on March 18, 2024; Edited on April 18, 2024.

The History of Challenges Relevant to the Interpretation of DNA Mixtures

         As an expert consultant in forensic biology/DNA, I am frequently asked by defense attorneys (I am rarely contacted by counsel for the prosecution) to educate them on various basic aspects of the emerging technology referred to as ‘probabilistic genotyping’ (PG). I explain that—while I am quite familiar with the fundamentals of PG technology—they might be optimally served by also requesting insights from forensic DNA mathematicians and/or experts who have actually developed PG software. I also emphasize that, as part of a good legal education on PG technology, they should scrutinize the history of DNA mixture interpretations.

When individuals working within the criminal justice system ask for advice on the fundamentals of forensic biology/DNA, I recommend the following: Any documentation published by the Scientific Working Group on DNA Analysis Methods (SWGDAM) will prove to be extremely useful. Link: https://www.swgdam.org/publications  Additional resources: DNA for the Defense Bar. (June, 2012), from the U.S. Department of Justice. Link:  https://www.ncjrs.gov/pdffiles1/nij/237975.pdf Two recent resources are: Forensic DNA Analysis: A Primer for Courts. (November, 2017), published by the Royal Society of Edinburgh: https://www.semanticscholar.org/paper/Forensic-DNA-analysis%3A-a-primer-for-courts/b503fc9202c4b6cc2ac783d326430b9402450987

and The Litigator’s Handbook of Forensic Medicine, Psychiatry, and Psychology. Within this reference set, Chapter 8 is entitled: “Forensic Use of DNA”. This reference is slated for publication during the first half of 2022. Requests for an advance copy of Chapter 8 can be directed to Michael J. Spence, Ph.D., at mike@spenceforensics.com

Analysis of evidence items can lead to the characterization of DNA mixtures with endless gradations of complexity and variability. From locus-to-locus, no two DNA mixture electropherograms (e-grams) will exhibit the identical ‘allelic landscape’. As Short Tandem Repeat (STR) typing initially became the basis of forensic human identification, law enforcement labs were not provided with sufficient centralized standards for the appropriate interpretation of DNA mixtures. Forensic DNA laboratory managers and their analysts were lacking direction. As this scientific obstacle became progressively recognized, and efforts were made to implement various guidelines, controversies and legal debates ensued.

It is useful to explore the evolution of efforts to address the misinterpretation of DNA mixtures. In 2005, forensic DNA scientists worked in concert with the National Institute of Standards and Technology (NIST), with the purpose of organizing a widespread inter-laboratory study of DNA mixture assessments. This initiative was referred to as the NIST MIX05 Study. Sixty-nine forensic DNA laboratories were provided with the identical two-person mixture data. Alarmingly, forty of the reporting labs characterized the DNA mixtures as “inconclusive”. Among the twenty-nine labs that provided a statistic—based upon non-exclusions—the random match calculations ranged from 1 in 31,000 to 1 in 213,000,000,000,000.

   

In recognition of this astounding lack of consistency, in February 2008, a DNA mixture interpretation workshop was held in Washington, D.C. This was one of a multitude of similar workshops—focusing in part, on the results of the MIX05 Study. Dr. John Butler—the acting chairman of this D.C. workshop—summarized the disturbing results with his presentation, entitled: “A High Degree of Variability Currently Exists with Mixture Interpretation.”

Part of Dr. Butler’s presentation included a commentary from the highly recognized forensic scientist, Dr. Peter Gill, which was as follows: “If you show 10 colleagues a mixture, you will probably end up with 10 different answers.” During the years following MIX05, many scientists expressed concerns, regarding the use of a simple inclusion/exclusion threshold for Relative Fluorescence Units (RFU). This presented a high potential for failure—as it encouraged what is affectionately referred to as the ‘Texas Sharpshooter Fallacy’ in forensic DNA interpretations. This fallacy is derived from an old tale describing a man (perhaps a Texan?) who test fires several bullets at the outer wall of an old barn. A thought dawns upon the man. He grins widely, and rushes off to grab some red paint, as well as some white paint. A few hours later, the man leads an assembly of friends and neighbors out to the old barn. The group is genuinely amazed at all of the painted targets on the barn wall—with a bullet hole perfectly located in the center of each target. Our primary character savors the outpouring of admiration.

His delight comes to an abrupt end when a savvy neighbor inspects the barn more closely—noticing that the paint is still sticky. The charade is completely exposed when the neighbor also realizes that some of the paint has been splashed through the obviously pre-existing bullet holes, and is dripping down the inside of the barn wall.

In 2008-2011, as scientists continued to wrestle with the DNA mixture interpretation version of this fallacy, a chasm formed between many forensic biologists/mathematicians—on one side, and the FBI/SWGDAM—on the other side. Refer to a 2011 article in Science and Justice, from the authors, Itiel Dror and Greg Hampikian. This article was entitled: “Subjectivity and bias in forensic DNA mixture interpretation”. In their conclusion, these authors addressed the forensic community as follows:

“…while this is the first published empirical study of potential DNA bias, Butler of the NIST laboratories has conducted extensive studies of mixture analysis over several years, wherein he supplies a large number of volunteer laboratories identical DNA mixture data and asks for their analysis. The results of these excellent studies have been presented at conferences and are available at the NIST webpages, but have never been published in a peer-reviewed journal. An interesting and perhaps the most critical point for this paper is that Butler’s research findings show that inclusion statistics for the same profiles (using the same data) varied over 10 logs, that is from 1 in 434,600 to 1.18 x 10¹⁵, using the exact same electropherograms.”

  

While the NIST MIX05 studies were illuminating, and may have somehow succeeded in nudging rational DNA mixture guidelines forward, harsh inconsistencies persisted for years to come. Around 2009/2010, the FBI and SWGDAM initiated a movement toward resolving this misinterpretation crisis by implementing a second, ‘stochastic’ RFU threshold. Apparently, the rationale of this movement was—if one threshold has proven ineffective toward resolving DNA mixture headaches, perhaps two thresholds might deliver a tangible improvement.

In 2013, NIST assessed this ‘binary threshold’ strategy, by organizing a new series of inter-laboratory surveys—referred to as the NIST MIX13 Study. Unfortunately, the outcome of the MIX13 study projected an unfavorable light on the binary approach. One hundred study participants were asked to assess a DNA mixture that included three contributors. One reference sample came from an individual who was known to be absent from this 3-person mixture. Seventy of the one hundred study participants incorrectly included this known individual. In addition to this appalling 70% rate of false inclusions, the random match probability of inclusion stats ranged from 1 in 9 to 1 in 344,000. Twenty-four of the one hundred study participants reported the comparison to the known reference as inconclusive. Only six participants correctly excluded the ‘innocent’ known individual. One of those participants utilized a PG software system—which is currently marketed as TrueAllele®.

Results from the NIST MIX05 and MIX13 studies were summarized within an August 1, 2018, publication in Forensic Science International: Genetics, under the following citation: John M. Butler, Margaret C. Kline, and Michael D. Coble, NIST Interlaboratory studies involving DNA mixtures (MIX05 and MIX13): Variation observed and lessons learned, Volume 37: Pages 81-94.

Within the first paragraph of the “Conclusions” section of this landmark publication, Dr. Butler and his co-authors warned scientists as follows:

“The results described in this article provide only a brief snapshot of DNA mixture interpretation as practiced by participating laboratories in 2005 and 2013. Any overall performance assessment is limited to participating laboratories addressing specific questions with provided data based on their knowledge at the time. Given the adversarial nature of the legal system, and the possibility that some might attempt to misuse this article in legal arguments, we wish to emphasize that variation observed in DNA mixture interpretation cannot support any broad claims about ‘poor performance’ across all laboratories involving all DNA mixtures examined in the past.”

This commentary from the authors is well-taken and agreeable. However, the flip-side to this warning is as follows: Those who manage law enforcement labs, as well as forensic DNA outsource labs, must be willing to openly acknowledge the fact that the comparative interpretation of complex DNA mixtures can present a formidable challenge to forensic biologists. They must also acknowledge that PG software technology has been developed—for the most part—with the objective of conquering the scientific concerns that have been propelled by the troubling, lengthy history of DNA mixture misinterpretations.

Here in early 2019—despite the increasing intensity of efforts aimed at establishing guidelines for reliable mixture interpretations—a clear consensus has continued to elude forensic labs. Within the 2018 DNA interpretation guidelines from one accredited crime lab (Source: Phoenix PD Crime Lab, Forensic Biology Procedures—DNA: Interpretation Guidelines.), the opening statement of this document acknowledges the following reality:

“The interpretation of results in casework is a matter of professional judgement and expertise. Not every situation can or should be covered by a predetermined rule.”

The Modern-Day Arrival of PG Software Systems: STRmix^TM

The STRmix^TM website informs us that: “STRmix™ is expert forensic software that can resolve previously unresolvable mixed DNA profiles. Developed by global leaders in the field, it uses a fully continuous approach for DNA profile interpretation, resolving complex DNA mixtures worldwide.” The makers of this software system assure their readers that “STRmix™ can easily be understood and explained in court by DNA analysts.”

STRmix^TM can be used to resolve relatively simple DNA mixtures, as well as complex mixtures, prior to factoring in the data from any known reference samples. Using well-established statistical methods, the software builds millions of conceptual DNA profiles.  It grades these profiles against the evidence sample, finding the combinations that logically justify the observations. Only after this has been accomplished, a range of Likelihood Ratio options are used for subsequent comparisons to known reference profiles. Specifically, STRmix™ uses a Markov Chain Monte Carlo (MCMC) engine to model peak heights of potential allelic data. The software also models various types of apparent stutter peak data, and factors in the possibility of allelic drop out events. All of these functions are performed rapidly by STRmix™.

The MCMC statistical approach provides a mechanism of sampling from any complicated distribution of data. Complicated distributions—such as the myriad of peak heights generated within a DNA mixture e-gram landscape—can be enormously challenging for probability calculations. Due to the fact that the performance of STRmix™ is being supported by comprehensive validation studies—with these underlying mathematics readily accessible to forensic DNA experts—the effectiveness of the software can be adequately summarized for jurors.

It is vital to recognize the reality that clarification of this technology for jurors can be most effectively accomplished in the hands of forensic DNA mathematicians and/or PG software developers. Clearly, the vast majority of crime lab analysts are not mathematical experts—nor are they likely to have developed any species of sophisticated software systems. It is faulty to conclude that any specialist in forensic DNA can be magically transformed into a mathematical expert—as a consequence of a brief PG analysis training program, coupled with plugging capillary electrophoresis data into a PG software system—such as STRmix™ or TrueAllele®.

If that were the case, any ardent couch potato could proceed as follows: 1) Skim through an ordinary television manual; 2) Become proficient with the TV remote control; 3) Grasp that an LED screen is composed of thousands of light pixels; 4) Study information on how images are captured during live broadcasts; 5) Review how images are transmitted via satellites, and funneled through dish receivers attached to homes; and voilà, the couch potato can now be passed off as a qualified expert on all aspects of the technology—including the mechanisms by which the technology is deployed.

On January 31, 2018, a Webinar was conducted, bearing the title: “From Training to Trial: A Reflection on Nearly Three Years of Probabilistic Genotyping.” This webinar was sponsored by Promega Corporation (the makers of PowerPlex® Fusion, among many other biotechnology products) Forensic Magazine, and the Institute of Environmental Science and Research (the birthplace of STRmix^TM). The two speakers within this webinar were technological leaders at DNA Labs International (Deerfield Beach, Florida). DLI was the first private laboratory in the U.S. to validate STRmix^TM. As part of this presentation, Ms. Rachel Oefelein (the Quality Assurance Manager, and a Senior DNA Analyst at DLI), offered the following advice to DNA experts testifying on the topic of probabilistic genotyping:

“Consider recommending an additional expert. We are not all John Buckleton. We are also not computer software programmers. So, there is no reason why you should have to explain—in great detail—what went into the developmental validation. You can only speak to what you know that you read from publications on the developmental validation…”

In contradiction to Ms. Oefelein's comments, a movement is apparently emerging—asserting that PG-trained crime lab analysts should have zero restrictions on their testimony to the reliability of this technology—whereas independent DNA consultants should be restricted from providing any commentary whatsoever. The rational is that independent DNA consultants have not received sufficient training on the theory, or the hands-on usage of PG software. Assertions resembling these are not new. Movements have emerged over the years—pointing to the fact that many independent consultants have not conducted casework in a forensic DNA lab for the past decade or so. Consequently, such experts should be restricted in their availability to testify in criminal proceedings—until they have achieved a substantial level of training/experience in methodologies that might include PG, real-time PCR, YSTR typing, GlobalFiler^TM, and PowerPlex® Fusion.

A profound hypocrisy has surfaced here. There is an existing subset of individuals who were at ground zero of the DNA mixture misinterpretation calamity that plagued our criminal justice system over the course of these recent decades. It is reasonable to suspect the existence of a meaningful overlap between those individuals—and the individuals who have been most emphatic—in the ridiculous push for infinite rounds of re-training for independent consultants in forensic biology/DNA.

Posted by Michael J. Spence, Ph.D. on January 23, 2019, edited on February 5, 2019, and edited again on January 10, 2022.