AUSTIN (KXAN) — During a pre-trial hearing for Meechaiel Criner, who is charged with the capital murder of UT student Haruka Weiser, the discussion turned to a debate over a new DNA testing method used in this case and whether the results should be permitted as evidence.
Criner, 19, who has pleaded not guilty, was arrested two days after Weiser’s body was found. Because he was 17 years old at the time of the homicide, Criner is not eligible for the death penalty if convicted.
The extent of his punishment would be life with the possibility of parole if found guilty of the murder.
In the courtroom, many parties discussed that the evidence in this case — both from Weiser’s body and from evidence near the scene — contains mixtures of DNA.
Having mixtures of DNA makes parsing out whose DNA is mixed in more complicated, so the STRmix testing was used aiming to pinpoint the probability that Criner’s DNA was in the evidence by comparing the likelihood that an unknown person’s DNA was in the evidence.
Attorneys Darla Davis and Ariel Payan are representing Criner.
On Monday, Judge David Wahlberg heard from state witnesses who feel the new STRMix testing used by the Department of Public Safety to test DNA profiles is scientifically valid. DPS began using this software in March of 2016.
Judge Walhberg stated frankly that, “all I know about DNA is how to spell it,” which is why the hearing quickly turned into an in-depth biology briefing for the whole courtroom.
The state explained that DPS used the STRMix computer program to determines the odds of a particular genotype being in an evidence DNA profile.
It’s a different technology for looking at DNA profiles than what was previously used. The state called Chase Baumgartner, the lead forensic scientist for DPS, forward. He explained that the old method “CPI” needed to be replaced because it could not be used if there’s any lack of genetic information.
The state also called forth a scientist from the Texas Forensic Science Commission who previously worked with DPS on testing the evidence from Weiser’s murder.
This witness said she was “infinitely more impressed” with STRmix than the other software she saw when DPS was looking into new options. She added that in general the commission she serves on sees probabilistic genotyping as valid science.
“We believe we’d be able to prove through numerous witnesses that is a scientifically accepted technique,” the state’s attorneys said.
But Criner’s attorneys feel differently.
“This is extremely complicated, I have been working on this for a year,” said Payan, who is challenging the validity of this method and the evidence in this case.
Payan believes that this case will be the first in Texas to make a challenge of this level to the use of STRMix for evidence. He noted that there have been other courts where challenges of STRMix have been successful, including one in New York.
“What we’re doing in challenging the system that is being used is challenging the underlying science that makes up the process, the actual application of that science in this particular case, and really the machine itself. You can’t cross-examine a machine, so that makes it hard,” Payan said.
“This is brand new and we think its too new for the application that’s being used here,” he added.
Payan said that it’s important to discuss the details of this DNA testing now because the scientific complexities of this may be challenging for juries to understand.
He believes the assumptions technology is built on come with “some basic flaws.”
Bob Wicoff, the director fo the Texas DNA Mixture Review Project, has used STRmix technology to retest DNA evidence numerous times.
“And we’ve gotten new results that in some cases made it much less likely that a person has left their DNA at a scene and in some cases made it much more likely, so it seems to work both ways,” Wicoff said.
Wicoff explained that there are several new technologies which aim to do what STRmix does, replace the old genetic testing systems by using probabilistic genetics.
“Nationwide, worldwide, sure this is not a Texas issue,” he said.
Wicoff couldn’t say which of these new technologies he thought works best, but said of all the probabilistic genetic testing he’s worked with, “I think it could be said without any question that this software is more accurate than the old way of doing this.”
On Tuesday, the judge explained that more witnesses for both the defense and the state will be called forward to talk about STRMix. The hearings are expected to continue all day Tuesday and half of the day Wednesday.