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Life Sentence for Murder Overturned by New DNA Technology

by Michael Fortino, Ph.D.

After nearly 10 years behind bars, Lydell Grant, now 42, is on his way to being exonerated after the highest criminal appellate court in Texas vacated his conviction following its review of revised DNA evidence analyzed through newly developed proprietary software known as “TrueAllele.” 

“I really believe that my story will be able to help someone else’s,” says Grant.

Nearly a decade ago, Grant was handed a life sentence in a Texas courtroom for the stabbing murder of Aaron Scheerhoorn outside a Houston gay bar in December, 2010.

To convict Grant, prosecutors relied mainly upon eyewitness testimony who described the assailant as black, age 25-30, and about 6 feet tall. Police believed the stabbing had been a “crime of passion.”

Following a tip describing the suspect’s car, an officer pulled over a vehicle in which Grant was driving just five days after the murder. At the time, Grant was driving on a suspended license. He also had an extensive criminal record that included aggravated robbery.

Seven witnesses then picked Grant out of a lineup as Scheerhoorn’s attacker. Throughout the investigation, Grant maintained his innocence, insisting he had never met Scheerhoorn and even produced an alibi for the time of the murder. 

Fingernail scrapings were collected from the victim and tested for DNA analysis at a Houston-based crime lab. The samples yielded a mix of two individual subjects, Scheerhoorn (victim) and an unidentified male. The Houston lab was unable to establish definitively that the second subject was Grant, although a State expert testified that Grant “could not be excluded.” The jury also heard from a witness who had corroborated Grant’s alibi, attesting that he had been with Grant the night of the stabbing. The jury chose not to believe the witness, and Grant was convicted of felony murder and sentenced to life.

From his Harris County prison where he said he felt “like an animal in a cage,” Grant began seeking legal assistance. His letter eventually reached the Innocence Project of Texas where it sat in a pile with hundreds, if not thousands, of other requests. Finally, in 2018, it was referred to the Texas A&M School of Law, which partners with the Innocence Project on case analysis.

Law students at A&M realized that Grant’s conviction had depended predominantly on eyewitness testimony, which is often skewed and inaccurate. They decided to take a second look at the DNA evidence.

In 2011, the Houston-based crime lab had used a traditional analysis technique on the Scheerhoorn sample in which a scientist gauges the results obtained from the sample to make a “probability” assessment. When the sample contains a mix of more than one subject’s DNA, as in this case, the graphic analysis is made more difficult and less reliable. Flawed DNA readings using this method have convicted innocent people, and there is no telling just how many innocent people remain behind bars today simply because they have not yet had access to new “21st century” proprietary software. 

Attorney Mike Ware, executive director of the Innocence Project, decided that a more careful analysis of the Scheerhoorn sample was necessary. Ware contacted an associate, Angie Ambers, associate professor of forensic science at the University of New Haven in Connecticut.

Ambers suggested a new type of DNA technology known as “probabilistic genotyping.” She informed Ware that there had been significant advances in DNA analysis technology since the time of Scheerhoorn’s murder. A proprietary software program called TrueAllele had been developed by a company in Pittsburgh known as Cybergenetics. The company had extensive experience with DNA forensic analysis, having deciphered samples from victims of the 9/11 terrorist attacks.

Ambers had the Scheerhoorn sample analyzed through TrueAllele and determined the Houston lab findings were likely flawed. A number of “Allelles” in the sample were absolutely inconsistent with either Scheerhoorn or Grant. But Ware, understanding the complexities of the justice system, knew that this information would not be enough to vindicate Grant.

Ware commissioned the Innocence Project to move its analysis a step further. It was suggested that Cybergenetics partner with a lab in South Carolina, which had access to the FBI’s DNA database known as the “Combined DNA Index System” or “CODIS.” CODIS contains the DNA profiles of 14 million convicted criminals and recent suspects.

Police and law enforcement labs regularly access CODIS for help with unknown DNA profiles, but CODIS is seldom available to private interests. With this exception, the collaboration between Cybergenetics, a private entity, and CODIS, a law enforcement database, meted out a successful match—a match that was not Scheerhoorn.

The missing DNA profile belonged to a Jermarico Carter, a man in Atlanta who had left Houston shortly after the Scheerhoorn murder. Carter, who also had an extensive criminal record, was interrogated by police and eventually confessed to killing Grant. Houston Police Chief Art Acevedo issued an apology to Grant and to his family, acknowledging “they have waited for justice all these years.” 

‘Historic Case’

The CEO of Cybergenetics, Mark Perlin, who was the developer of the TrueAllele software algorithm, noted that this was a historic first use of the “probabilistic genotyping” software in response to a third-party request involving a private enterprise (Innocence Project) accessing a law enforcement database. A collaboration, in this case, that, as a result of this new software, successfully yielded a match. “There’s probably 5,000 to 6,000 innocent people in Texas prisons alone,” said Ware of the Innocence Project. “How many of them could benefit from such a reanalysis of DNA that was used to convict them? I don’t really know, but this is a historic case that could open the door for those who thought it was shut forever.”

Still, while TrueAllele has helped both the prosecution and defense in several cases across the country, the software has attracted criticism. The fact that the software is proprietary and can produce results that may only be deciphered exclusively through Cybergenetics, proprietary code introduces a confidentiality problem for those who may wish to challenge its findings in court.

Greg Hampikian, a biology professor at Boise State University, stated it is problematic for a defense team to be sufficiently trained to “counter the highly sophisticated mathematical programs without having actually used them.”

Defense expert Dan Krane feels that if “probabilistic genotype” software is going to be used within criminal proceedings, defendants have a right to know how results are obtained when such results may be detrimental to their case.

There is now an increasing number of cases in which proprietary software has been challenged by evidentiary suppression motions, forcing judges to demand that companies reveal the inner-workings and trade secrets associated with their brainchild (the software’s algorithmic source code). 

Cybergenetic’s Mark Perlin claims that TrueAllele’s source code is a “trade secret,” and one that needs to be protected in a “highly competitive commercial environment.”

Likewise, CODIS remains under the control of the FBI and has proven difficult to access, if not wholly inaccessible to labs representing the private sector. 

These conflicts between legality, constitutionality, and science will likely continue. Democrat Representative Mark Takano of California introduced legislation in September 2019 that would require defendants have access to “all” source code and standards in an effort to accurately evaluate the fairness of algorithm use.

The Justice in Forensic Algorithm Act is now in the hands of the Judiciary Committee and The Committee on Space, Science and Technology.

As to how quickly and expeditiously our legal system can leave the 19th century behind, and embrace 21st century technologies, remains a highly debatable subject. In the interim, it is impossible to know how many other “Lydell Grants” are out there languishing in prison and awaiting justice. 



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