UT murder suspect’s defense poking holes in new DNA analysis method

Austin

AUSTIN (KXAN) — The challenge to the new method of genetic probability testing used by the Texas Department of Public Safety continued Tuesday in a Travis County courtroom. This is all part of the pre-trial proceedings for Meechaiel Criner, the suspect charged with capital murder in the death of University of Texas student Haruka Weiser.

As Criner sat in court, attorneys went back and forth about the way DNA was analyzed from Weiser’s murder in a process they plan to accomplish before a jury is selected. Many of the details of this DNA analysis debate are extremely complicated, leaving many in the courtroom glassy-eyed and asking questions. 

The heart of the debate is the STRmix software which DPS began using in March of 2016. This STRmix software is used in 31 labs around the country and four DPS labs in Texas. The state believes it is reliable but the defense is trying to prove it’s not. The defense told KXAN they believe they are the first ones to challenge the use of the STRmix software at this level in Texas

The court heard yet again from Chase Baumgartner, the lead forensic scientist for DPS, who explained that DPS staff tested the STRmix software and while they only found error ratings of a fraction of a percent, they found that the software could not handle a DNA mixture which contained five people or more. As discussed in the courtroom, the more people’s DNA is included in a mixture, the more room there is for error.

The rest of the day was spent with one particular witness: Jody Koehler of the Texas Forensic Science Commission. Koehler previously worked as a lab report analyst for DPS and looked over some of the DNA reports from Weiser’s case when DPS analyzed them. 

The questions Tuesday focused on the examination of one particular piece of evidence: the first swab of DNA taken from Weiser’s thigh showed that Criner’s DNA was not part of that DNA mixture when it was tested.

The second swab of DNA from Weiser’s thigh was tested first manually by Koehler, as is standard practice when using STRmix. Koehler, who has been testing DNA since the 1990’s had been used to a certain way of operating, and the adoption of STRmix meant changing some of the steps in her process. When she tested the second swab by hand, the presence of genetic material was too low for Koehler to draw a conclusion, so she labeled the result inconclusive. But, when she exported her dataset through STRmix, the machine told her that she could not exclude the possibility that Criner’s DNA was in that evidence. 

When the defense wanted to see original documentation of one of the versions of this test Koehler did, the tone in the courtroom grew tense as the state said they’d already provided the data, and the defense replied that they wanted to see the original document and see if Koehler had handwritten any notes there. Koehler doubted the document the defense was looking for existed. 

At that point, Judge David Wahlberg said he was concerned and was inclined not to admit that evidence altogether. But ultimately he decided to wait on making a decision about that piece of evidence until further notice. 

The hearing will continue at 9 a.m. on Wednesday. There are more witnesses and evidence set to be discussed. The court is aiming to finish these hearings before a jury is selected and the trial begins for Criner, who could face life in prison with the possibility of parole. 

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