DNA testing problems inside CMPD crime lab cause court delays, retests
Court officials are delaying cases and retesting evidence following reports that a DNA analyst intentionally manipulated tests inside Charlotte’s police crime lab, the Mecklenburg District Attorney’s Office said.
An unnamed DNA analyst working in Charlotte-Mecklenburg Police Department’s crime lab was last year found changing a part of the DNA testing procedure that ensures results are accurate, The Charlotte Observer reported after obtaining a letter CMPD’s lab director sent to an accreditation board.
The reported tampering has raised questions about reliability in a lab that, according to CMPD’s website, tests evidence in local, state and federal cases. The irregularities have delayed an unknown number of cases and “demanded retesting,” district attorney spokesperson Mike Stolp wrote in a statement to the Observer.
Questions over lab analyses “generally result in a delay in a case until the lab file can be thoroughly reviewed and vetted to ensure its accuracy,“ Stolp wrote.
After learning of the problem last March, District Attorney Spencer Merriweather asked the North Carolina State Bureau of Investigation to determine if the analyst violated criminal law.
The SBI recently gave Merriweather a “voluminous” report, Merriweather said in March. After reviewing it, Merriweather had more questions, he told the Observer this week. The SBI is continuing its investigation, per Merriweather’s request, and expects to answer the new questions within the next month, said SBI public information officer Chad Flowers.
Attorneys working on affected cases have been notified, according to the DA’s office.
CMPD did not respond to a request for comment.
Manipulated DNA testing
CMPD crime lab director Matthew Mathis in a letter previously obtained by the Observer said an internal investigation began following reports that an analyst “manipulated a positive control during the DNA testing process.” Positive controls are known DNA samples tested at the same time as new DNA samples. They are used to ensure procedures are working correctly.
CMPD’s initial investigation found that when this routine test failed, the unnamed analyst “intentionally substituted” the failed positive control with a different sample that was “known to give the expected positive result,” according to the letter.
The analyst was placed on unpaid administrative leave, according to the letter, which was sent to to a national lab accreditation board.
Has your court case been affected by the NCSBI investigation into CMPD’s crime lab? Contact reporter Julia Coin at jcoin@charlotteobserver.com or (704) 218-9350.
This story was originally published June 13, 2025 at 11:51 AM.
