Commonwealth v. Read — Trial Archive
Person Tess Chart Trial 1Tess Chart is a DNA analyst at Bode Technology who testified in Trial 1 about mitochondrial DNA testing linking a hair sample to John O’Keefe. ← All People
🔬 Expert Witness · Bode Technology

Tess Chart

Trial 1
66 lines 1 proceeding
Courtroom still of Tess Chart.

About

Tess Chart is a forensic DNA analyst employed by Bode Technology, a private laboratory accredited by ANAB and the FBI. She testified in Trial 1 on Day 24 about mitochondrial DNA analysis performed on a hair sample recovered from Karen Read's vehicle. Her testimony established that the hair sample was consistent with John O'Keefe's mitochondrial DNA profile and that at least 99.89% of the population could be excluded as a possible source.

Key Points

  • Chart explained that mitochondrial DNA testing was employed because the hair sample lacked sufficient nuclear or autosomal DNA — a common limitation with shed hairs — making the mitochondrial approach the only viable method for generating a profile.
  • She presented the central finding of her analysis: the mitochondrial DNA profile obtained from the hair sample was consistent with the reference profile taken from John O'Keefe, placing the hair evidence within the prosecution's narrative that O'Keefe had contact with Read's vehicle.
  • Chart quantified the statistical significance of the match using the EMPOP population database, testifying that at least 99.89% of the population could be excluded as a source of the hair at the 95% confidence interval, lending scientific weight to the identification.
  • The defense waived cross-examination of Chart entirely, leaving her direct testimony and statistical conclusions unchallenged on the record.

Trial Record (1)

Trial 1 First Criminal Trial Apr 29, 2024 – Jul 1, 2024 1 proceeding

Day 24

Direct Tess Chart Adam Lally 3 highlights 65 lines spoken
Summary

Forensic DNA analyst Tess Chart testified that hair sample EO1 was consistent with John O'Keefe's mitochondrial DNA profile and supported an exclusion of at least 99.895 percent of the population.

Highlights (3)
Quote

“So the mitochondrial profile that was obtained from the sample, the hair sample, was consistent with the mitochondrial DNA profile obtained from John O'Keefe. So, therefore, John O'Keefe cannot be excluded as a possible contributor of that hair.”

Chart stated her comparison conclusion for the hair sample and O'Keefe's reference profile.

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Quote

“Sure. So by not seeing it in the database, this means that we are able to exclude at least 99.895 percent of the population from being a source of that evidence.”

Chart gave the statistical exclusion she associated with the database comparison.

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