State lab error forces 52 cocaine cases to be retested

PROVIDENCE – Accidental cross-contamination during a quality control test at a state laboratory is calling into question hundreds of criminal cases involving cocaine.

The R.I. Department of Health revealed on March 17 that a scientist at its Forensic Drug Chemistry Laboratory detected cocaine during a routine quality assurance testing last fall, in a sample that was not supposed to contain the drug. This was likely caused by carry-over contamination from another sample, the agency said.

The department notified the R.I. Office of Attorney General, which requested review of all affected cases – all criminal cases in which samples involving cocaine were tested by the scientist in question. After a review, the DOH determined it will retest 52 law enforcement cases, while an additional 263 cases are still pending review.

At the Forensic Drug Chemistry Laboratory, scientists routinely perform proficiency testing, in which they are given samples to test for substances. The scientist that detected cocaine in the sample has been removed from testing other criminal cases that potentially involve cocaine “until they can be retrained on updated procedures and best practices,” RIDOH said. The lab also reviewed 13 years of laboratory proficiency testing results and found there were no other cases of false detections.

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Details of the incident were described in a March 17 letter by Glen Gallagher, director of Rhode Island State Health Laboratories, to the attorney general’s Narcotics and Violent Crime Unit.

Officials reviewed all samples tested by this scientist from June 2021 – when the scientist was first approved for testing powder substances – to November 2022, when the false detection occurred. In this time frame, the scientist examined samples from 1,313 cases: 549 cases did not contain any detections of cocaine, so they were unaffected, while the remaining 488 with detected cocaine were tested to determine the signal strength.

RIDOH ruled out 436 cases in which the signal was strong enough to indicate “high confidence” that cocaine was present and where therefore cross-contamination was not likely. In the end, 52 cases had a weak signal and are being retested. RIDOH said it is expediting the retesting of any of these cases and will retest them as soon as they are submitted by law enforcement.

“FDCL would need to do re-testing to determine whether the small amounts of cocaine included in these 52 law enforcement cases were the result of carry-over contamination,” RIDOH said in the letter. “If evidence on these cases remains and can be retrieved from law enforcement agencies for re-testing, re-testing will be done immediately.”

For another 263 cases, the impact is still being determined, RIDOH said, as they involve samples with less than 10 grams of controlled substances. RIDOH said cocaine, unlike other substances, is particularly susceptible to cross-contamination because of its fine particles and the sensitivity of the instruments used for testing. This is why only samples involving cocaine are being reviewed.

The Attorney General’s Office said it is working to identify impacted cases, send notices to defense counsels representing the defendants and notify police departments.

“That process has been time consuming as the list of cases sent to us by the lab does not include corresponding court case numbers,” said R.I. Attorney General Peter F. Neronha in a statement released on March 17. “We have been working to identify all pending and disposed cases as well as cases where the defendant may be held or serving a sentence at the ACI. At this juncture, it does not appear that any defendant is held solely based on charges involving cocaine.”

Neronha said his office has briefed the Rhode Island Public Defender office, the presiding and acting presiding justice of the R.I. Superior Court, the presiding justice of the R.I. District Court, the Rhode Island Police Chiefs Association, and the R.I. State Police.

“Following our initial action, we will continue our work to evaluate the scope and impact of this issue, and expeditiously work with stakeholders to ensure that no individual’s rights have been violated,” Neronha said.

Claudia Chiappa is a PBN staff writer. You may contact her at