The Austin Police Department has temporarily suspended operations at its DNA lab because of concerns raised by the Texas Forensic Science Commission, a lack of properly trained supervision and the need to allow staff to learn a new federally required way of verifying evidence, the American-Statesman and KVUE-TV have learned.
The decision means that hundreds of DNA samples — often crucial evidence in crimes such as homicides and sexual assaults — will either be shipped to the Texas Department of Public Safety lab or to private labs for analysis, possibly delaying the outcome of pending cases in already backlogged Travis County criminal courts.The article declared that the closure "comes at a time when DNA labs nationally are adapting to new federally required procedures." However, when I emailed the FSC's Lynn Garcia, she said she's "not sure what federal guidelines they are referring to." Really APD just screwed up the science, using a method which is "neither scientifically valid nor supported by the forensic DNA community," according to the six-page letter from the FSC to Austin PD critiquing their methods, which Garcia provided to your correspondent.
Embarrassingly, according to the letter, the main problem was that lab personnel didn't understand past federal directives: "Technical Leaders (TLs) and senior analysts in the APD DNA Lab appear to have misunderstood language from the Scientific Working Group on DNA Analysis Methods (SWGDAM) Interpretation Guidelines for Autosomal STR Typing by Forensic DNA Testing Laboratories ... and from Dr. John M. Butler's textbook, 'Advanced Topics in Foensic DNA Typing: Methodology.'"
"Of greater concern, the analysts themselves were aware the [method] was ineffective because they observed ... [problems] in their own casework" and did nothing. They cherrypicked data, choosing which loci to compare based on whichever ones show up in the sample. "The appropriate approach is to decide which locus (or lici) should be used first ... as indicated by the overall analysis of the evidentiary sample, not on which alleles are present or absent based on the victim or suspect known profiles."
The FSC identified at least one case where contamination made APD's results invalid, as confirmed later by a private lab. They also found ten cases of contaminated reagents.
Worryingly, the problems were not revealed by ASCLD/LAB assessments, even though deficiencies were evident in the data they were given.
These observations raise legitimate questions regarding the limits of accreditation and the consistency of assessor teams. Specifically,: (a) Are the scope and limitations of accreditation well understood by the criminal justice community? (b) Do assessors consistently consider whether the laboratory's protocols and underlying validation based on sound scientific principles or do they limit their review solely to determining whether the laboratory has a protocol in place that it follows? (c) Should assessors re-review validation data from prior years considering that validation studies are relied upon to build subsequent protocols?Most of that detail wasn't included in the Statesman story.
Concluded the paper, "the Austin Police Department’s crime lab, which will have to recalculate statistics on about half of the 1,297 Travis County cases identified so far, is still validating new software and updating its protocols. Meanwhile, the lab’s backlog of cases awaiting DNA analysis has risen to about 1,300, the most in the past five years."
It's a mess, but it's not that different than what most other crime labs in the state are going through, except most of them didn't shut down operations until their staff are retrained. After all, the errors relate only to mixtures. There are still quite a few cases, including most rape kits, where there is only one unknown sample. That part Grits finds odd, but I'm glad they're belatedly getting their act together on this topic.
MORE: From Forensic magazine.
See prior, related Grits posts:
- A reluctant scoop: Changing interpretations of DNA mixtures vex legal system
- Labs must correct wrong DNA mixture analyses, learn when to recognize 'crap'
- Resources on DNA mixtures
- The challenge of notifying defendants in large-scale forensic error cases
- DNA mixture SNAFU a mess but don't expect 'deluge' of innocence claims