A Florida crime lab employee has resigned during an investigation into missing drug evidence.

Joseph Graves submitted a resignation letter Monday, two days after the agency announced an investigation into missing evidence that could compromise hundreds of cases.

The Florida Law Enforcement Department confirmed the resignation of a chemist who is suspected of substituting non-prescription drugs for prescription painkillers. When The Associated Press asked for the suspect's resignation letter, the department released a copy of Graves' letter.

The agency is now reviewing 2,600 cases the employee handled involving 80 law enforcement agencies in 35 counties. The suspect has not been formally charged.

Contact information for Graves could not immediately be located.