Texas Computer Algorithms Improving Accuracy of Convictions

Learn About the DNA Algorithm Responsible for Exonerating an Innocent Man 10 Years into His Life Sentence

DNA testing produces strong evidence in criminal convictions, though the science behind it has long been prone to errors and inaccuracies. Certain groups have dedicated their work to further investigating and improving forensic science and, with new code and cyber applications, are improving the capability of DNA testing.

How DNA Evidence Can Be Problematic

DNA evidence, though perceived as irrefutable, holds a dangerous potential for error and imposed problems. DNA evidence can be sullied in many ways, including:

  • Mixtures, where more than one person contributes to a sample
  • Degradation, where samples have aged or been exposed to harsh conditions, thus making the information more difficult to interpret
  • Stutter peaks, where DNA fragment copies may show an additional repeated peak or one fewer peak than the true fragment being examined because of the small rises occurring before or after real peaks on electropherograms
  • Peak height imbalance, where there is more than a 30% difference in height between peaks, indicating likelihood of a mixture
  • Blobs and noise, where dye can mask allele in the electropherogram, or bubbles or contamination are present that can lead to false interpretation of the data
  • Pull-up or bleed-through, where the software failed to differentiate between dye colors used in separate samples
  • Spikes, where voltage spikes cause artificial peaks on readings
  • Raw data problems, where the baseline is not constant and is generally uneven

Reevaluating Questionable Results to Free Lydell Grant

In 2012, Lydell Grant was wrongfully convicted for a murder outside of a Houston bar that took place two years prior. A key element in his conviction was a presentation of DNA collected from the victim. The sample had the DNA of the victim and an additional male. While Houston labs could not conclude that the DNA was Lydell’s, they suggested the possibility could not be entirely excluded.

Despite his alibi, Lydell was sent to jail for first degree felony murder. He immediately took to writing out to anyone who could help him prove his innocence. His story was eventually received by the Innocence Project of Texas, a local group devoted to fighting for the exoneration of innocent individuals, and the Texas A&M School of Law, with which the group partners.

The DNA sample was centric in the law students’ reevaluation of the case. The sample was analyzed using a traditional method that, when dealing with a mixture of DNA, makes it more difficult to read the data.

Lydell’s samples were evaluated in 2011. Mere years after his conviction, casework protocol shifted to using computer software programs rather than human analysts like in his case. The Innocence Project of Texas requested the raw DNA data from the case and collaborated with one of these genetic programs, TrueAllele by Cybergenetics. The program was able to determine that Lydell’s DNA did not match that of the second unknown male in the sample.

The team moved forward and utilized connections that Cybergenetics had. They partnered with a South Carolina crime lab with access to the Combined DNA Index System (CODIS) used by the FBI. By uploading the unknown sample to the database, the group found a match: Jermarico Carter.

The Future of DNA Tracing

Mark Perlin, CEO of Cybergenetics and developer of TrueAllele, is making substantial strides in the field for his efforts in minimizing errors and entanglement in DNA tests. TrueAllele runs samples through a statistical algorithm designed to untangle DNA mixtures. Through the software’s 170,000 lines of code, it can effectively identify the patterns of each person’s DNA and any distortions.

While the program marks a significant scientific achievement, many question the reliability of it long-term when the company has privatized the code it uses to conduct the tests. Transparency will be a leading concern for the future of digital DNA testing and tracing.

Call The Law Office of Rene A. Flores PLLC for professional criminal defense from a scientist lawyer: (956) 606-3606.