A CMPD analyst manipulated DNA testing, but was it criminal? DA will decide
A Charlotte-Mecklenburg crime lab analyst accused of intentionally manipulating DNA testing processes could face criminal charges after a nearly year-long investigation.
Mecklenburg County District Attorney Spencer Merriweather asked the North Carolina State Bureau of Investigation last March to investigate the analyst, who authorities have not named, and determine if the analyst violated criminal law by tampering with the DNA testing process.
The SBI turned over its findings last week, and Merriweather must now review the case file and decide whether or not to press charges.
No new details on the investigation have been revealed, but The Charlotte Observer earlier this month obtained a letter CMPD Crime Lab Director Matthew Mathis sent to a national board that accredits U.S. crime labs last March.
‘Manipulation’ in CMPD crime lab
CMPD’s Crime Lab is responsible for testing evidence such as DNA, blood, fingerprints, firearms and documents for county, state and federal agencies. Its “state-of-the-art forensic analytical services” test evidence in cases managed by local, state and federal authorities, according to CMPD’s website.
The CMPD analyst under investigation allegedly “manipulated a positive control during the DNA testing process,” according to Mathis’ letter.
When analysts test new DNA samples, they at the same time test a known DNA sample — known as a “positive control” — to make sure their 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.
Control failures could indicate testing issues and unreliable results.
As of a year ago, CMPD was investigating “the full scope of the issue,” according to the letter. Merriweather previously said his prosecutors have worked to “identify both pending and previously resolved cases that may be impacted by this discovery.” He also said his office would notify defense attorneys if tests affected by the analyst’s actions involved defendants they represent.
In a statement last year, CMPD Chief Johnny Jennings said the analyst deviated from “standard control sample protocols” and that “there was no manipulation of any evidence.”
But an evidence-testing procedure was manipulated, according to Mathis’ letter.
The SBI’s investigation into CMPD’s lab analyst is “voluminous” and will take Merriweather’s office weeks to review, he told the Observer Tuesday.
CMPD and Mathis did not respond to request for comment.
This story was originally published March 12, 2025 at 5:00 AM.
