Hundreds of drug cases in Prince George's County may be in jeopardy because of allegations by a former employee of the county's police drug lab that the facility botched tests of drugs in criminal cases and assertions that prosecutors knew of possible improprieties and failed to notify defense attorneys.

The Prince George's County public defender's office has filed more than 50 requests for continuances in pending drug cases and has asked judges to direct the state's attorney's office to provide detailed information about the drug lab's methods, its analysts' qualifications and the conditions of the lab's instruments.

The motions have been filed in adult and juvenile drug cases that date to November, when the former lab employee alleges she made prosecutors aware of irregularities in the lab and they dismissed a drug case in which she was scheduled to testify.

State and federal law requires prosecutors to make defense attorneys aware of evidence or information that might clear their clients.

The lab, at police headquarters in Landover, tests samples in about 3,000 cases a year, police said. The state's attorney's office prosecutes about 1,200 felony drug cases and about 6,000 misdemeanor drug cases annually.

Chief Administrative Judge William D. Missouri has scheduled a hearing on the defense motions for Wednesday. Circuit Court Judge E. Allen Shepherd will consider the motions--which contain identical language for all the defendants--collectively, Missouri said.

State's Attorney Jack B. Johnson (D) said yesterday that he was aware of the November dismissal but that he has no reason to believe there were or are widespread problems with the lab and therefore has nothing to tell defense attorneys.

"My office never has and never will cover up anything," Johnson said. "I don't believe there is any basis for these motions."

An internal police investigation found no credence to the former employee's allegations, according to documents filed in the woman's civil lawsuit against the police department.

Johnson noted that in March 1995, he dropped 10 felony drug cases after Edwin Brown, then the lab's director, mistakenly identified a sample as cocaine. All were cases in which Brown had personally tested the alleged drugs and the evidence was lost or destroyed.

Royce D. Holloway, a police spokesman, said the 12-year-old lab follows all state guidelines in its testing procedures.

But the crux of the defense attorneys' current challenge concerns their contention that they should have been made aware of the former employee's allegations.

In an Aug. 10 letter to Johnson, county Public Defender Joseph M. Niland said he intends to ask court officials for an independent audit of the police lab.

The public defender launched the legal challenge after he and some of his attorneys met with Kellie Lynn Campbell, 28, a former police drug lab chemist who alleges in her civil suit that she was fired after she told prosecutors of alleged improprieties and incompetence in the lab.

Campbell's lawsuit, filed in U.S. District Court in Greenbelt, alleges that Police Chief John S. Farrell fired her March 12 because she tried to speak out about problems in the lab.

Campbell's attorney, Francisco J. Ruben, said Campbell decided to meet with the public defender's office after talking to a representative of a whistleblower's rights organization.

According to the lawsuit, Campbell told Assistant State's Attorneys Toni Drake; David Whitacre, chief of the major crimes division; and Wanda Dixon, chief of the narcotics section, on Nov. 4, 1998, that test results in some criminal cases were not reliable.

Campbell told the prosecutors that lab manager John Porter had made errors in some tests and had ordered her not to retest any drug samples, according to the lawsuit.

"From March through approximately July, 1998, Porter continuously and improperly calibrated various pieces of forensic equipment, making the drug analysis results unreliable in many instances," the lawsuit alleges. "On several occasions, he also broke several pieces of the forensic equipment, some repeatedly."

"Porter refused to acknowledge that any of the forensic equipment had malfunctioned, calling into question several months of forensic data used to convict criminals currently serving sentences in Maryland prisons," according to the lawsuit.

Campbell identified several drug cases for the prosecutors in which there were apparent problems with test results, according to the lawsuit.

Citing the pending lawsuit, Porter declined to comment yesterday. County Attorney Sean Wallace, whose office is defending the police department in the Campbell lawsuit, was away from the office yesterday, staff members said. Wallace's deputy did not respond to a phone call seeking comment.

Two days after her meeting with prosecutors, Campbell was notified she was being placed on administrative leave and investigated by the police internal affairs unit, according to her lawsuit. Three days after that, internal affairs investigators questioned her about the information she had provided to prosecutors about the drug lab, according to the lawsuit.

A subsequent police internal affairs report said investigators had determined that Campbell had made untrue statements to prosecutors and had failed to prepare a drug case assigned to her for trial.

In an interview, Campbell said she spoke out about what she saw as problems in the drug lab because, "I had an obligation as a scientist. If I thought there was a problem with a case, it was my obligation to present that. . . . I thought the attorneys would handle it appropriately."