A report released Thursday found that problems at the Nassau County lab went largely undetected, were ignored, or were not properly addressed.
Ellen Biben's report cites failures at all levels of the lab's management and oversight.
The inspector general opened an investigation earlier this year.
Officials closed the lab in February when problems with evidence were detected.
Evidence in hundreds of drug cases is being reviewed. At least one drunken driving conviction was vacated because of issues with lab evidence.
A national accrediting agency placed the lab on probation in late 2010 for failing to meet national standards.
A police spokesman said officials would not comment until they've had a chance to review the report.