MINEOLA, N.Y. (CBSNewYork/AP) – Marijuana that was to be used as evidence in a Long Island drug case has disappeared from a truck that was transporting it to a Pennsylvania crime lab.

Marc Gann, head of a committee examining problems at the Nassau County police crime lab, said it appears someone had tampered with and potentially stolen some of the evidence that was placed FedEx’s custody.

He said the district attorney’s office told him a shipping box on the FedEx truck had been opened, the marijuana removed and the box resealed.

“It just calls into question the propriety of dealing with a common carrier, like FedEx, for purposes of delivering evidence,” Gann told 1010 WINS. “Perhaps a better course of action would be to use an employee of the police department or the county.”

It’s the latest fallout from the shutdown of the Nassau crime lab. A national accrediting agency has put it on probation for failing to meet protocols deemed essential to proper handling of evidence. Since its closing in February, evidence has been shipped to a lab in Willow Grove, Pa.

FedEx is looking into the possible theft. The DA’s office says it’s investigating.

Gann said the case which the marijuana was connected to is now “completely unprovable.”

“It raises a broader issue about the credibility of the evidence in those other cases that were being transported along with the marijuana,” he said.