(CNN) -- The fallout of an investigation into a drug testing lab could cause some trials in Delaware to be postponed for months.
Delaware State Police investigators have taken control of the lab inside the state's Office of the Chief Medical Examiner after discovering drug evidence submitted to the lab for analysis had been tampered with, substituted or gone missing, a state police spokesman said Monday.
State investigators, along with the Delaware Attorney General's Office, launched a joint investigation late last month when a sealed evidence envelope was opened in court during a drug prosecution in Kent County and prosecutors discovered Oxycontin pills had been replaced with blood pressure medicine.
The drug lab is sealed as police inspect and audit the drugs in evidence there, and the lab has stopped conducting drug analysis.
State police spokesman Sgt. Paul Shavack said it is too early to know how many criminal drug cases might have been affected.
In light of the investigation, the state has requested all pending trials involving drug evidence submitted to that drug lab be stayed for 60 days.
Police say there are no charges pending.
Police departments around the state have been asked to audit their own drug evidence for any potential evidence tampering.