SAN FRANCISCO -- The state attorney general will be sending in experts to access the problems at the San Francisco Police Crime Lab in the wake of a scandal that has led to the release of at least 60 drug suspects who were awaiting charges.

Assistant District Attorney Brian Buckelew told KTVU that an additional 30 drug suspects may be released on Friday.

State Attorney General Jerry Brown said it was "critical" that the lab be reopened as soon as possible and San Francisco begin to once again move ahead on drug cases.

Officials said that about 60 cases have been dismissed since Tuesday night and that the normal flow of 16 to 20 new cases filed a day had come to a halt.

"My office will assist San Francisco police to get to the bottom of these serious evidence-tampering allegations," Brown said in a prepared statement. "It's critical that we act immediately to get the San Francisco crime lab back in service and restore the public's trust in our criminal justice system."

At the request of San Francisco Police Chief George Gascon, crime lab specialists from Brown's office will assist San Francisco authorities in re-testing of evidence, improving internal controls and taking whatever steps are necessary to return the lab to full operation.

Gascon admitted Thursday that the department "made a mistake" by not disclosing the prior criminal history of a former crime lab employee being investigated for stealing drug evidence, but insisted that should not force scores of court cases to be tossed out.

The revelation that the former civilian lab supervisor, 60-year-old Deborah Madden, may have taken small amounts of powdered cocaine from evidence containers resulted in Gascon's order earlier this week to temporarily cease drug testing at the lab.

Madden was convicted in San Mateo County in 2008 of misdemeanor domestic violence, but Gascon -- who was hired last year -- admitted at a news conference this afternoon that the department never told prosecutors or defense attorneys.

"We made a mistake," Gascon said. "We had a system failure and we failed to disclose." He called it "a technical violation" and added that it would be "grossly overstating the case" to say that would be cause to overturn "hundreds, perhaps thousands" of prior drug cases.

That was a reference to statements Public Defender Jeff Adachi made to reporters Wednesday suggesting there was cause to overturn those cases. Adachi noted that Madden may have directly or indirectly handled "hundreds, if not thousands" of prior cases, as well as testified in many cases. He said defense attorneys are required to be notified if a witness has a prior criminal conviction.

Gascon did not mention Adachi by name.

"Those cases that were prosecuted had every legal basis to move through the criminal justice system," Gascon insisted. "We must not lose sight of the fact that these convictions were based on a thorough forensic analysis and were constitutionally sound."

"There was no fabrication of evidence; no one was framed for crimes they did not commit, and the misconduct was limited to a small number of powder cocaine cases," Gascon said.

According to Gascon, Madden admitted the alleged taking of evidence began in October 2009. "We don't know if that's true or not," he acknowledged.

Madden took a leave from the department on Dec. 8 and officially retired on March 1.

According to Gascon, he became aware of the missing drugs in late February. Police delivered a search warrant to her San Mateo home on March 3, and found a gun and "what appeared to be coke," he said.

Madden was arrested by San Mateo County authorities because, with a prior conviction, she was prohibited from possessing a firearm. She has not yet been charged in connection with the crime lab investigation.

Both Gascon and the district attorney's office have emphasized that some of the cases would be re-filed after the alleged drug evidence is tested at labs in neighboring counties.

The temporary cessation of drug testing at the San Francisco crime lab has forced prosecutors to abandon dozens of new and existing cases and release many arrested for drug sales or possession back onto the streets.

"They have not gotten off the hook," Gascon said. "We're not giving up."

Gascon also said the department would continue buy-bust undercover operations in the Tenderloin. Buy-bust arrests constitute the majority of drug cases brought by San Francisco prosecutors.

"Our commitment to the community is as strong as ever," Gascon said.