Updated

Reformed after controversy in the mid-1990s, the FBI crime lab is dealing with new wrongdoing by employees that has opened the door for challenges of the lab's science in scores of cases involving DNA and bullet analysis, internal documents show.

One FBI lab scientist, who connected suspects to bullets through lead analysis, has been indicted after admitting she gave false testimony, and a technician has resigned while under investigation for alleged improper testing of more than 100 DNA samples, according to records and interviews.

In addition, one of the lab's retired metallurgists is challenging the bureau's science on bullet analysis, prompting the FBI to ask the National Academy of Sciences to review its methodology, the records obtained by The Associated Press show.

FBI Lab Director Dwight Adams said detection of the problems illustrates that reforms are working.

"The difference is these are being caught and dealt with swiftly. Our quality assurance program is in place to root out these problems, incompetence and inaccurate testimonies," Adams said in an interview. "These weren't fortuitous catches; they were on purpose."

Defense lawyers are already mounting challenges in high-profile cases handled by the two employees and are questioning the FBI's project to build a national DNA database that will help law enforcement identify suspects based on their genetic fingerprints.

"We all have assumed the scientists are telling the truth because they do it with authority and tests. And as a result FBI scientists have gotten away with voodoo science," said Lawrence Goldman, president of the National Association of Criminal Defense Lawyers.

The Justice Department's internal watchdog is investigating FBI lab technician Jacqueline Blake for allegedly failing to follow proper scientific procedure when analyzing DNA in at least 103 cases over the past few years, officials said.

The officials said they have found that the technician failed to compare the DNA evidence with control samples, a required step to ensure the accuracy of tests. Blake resigned from the FBI lab recently.

Blake's work has become an issue in a prominent case in New Jersey, where five police officers are challenging blood evidence she analyzed that was used to convict them of federal civil rights violations in the death of a prisoner.

FBI officials have already taken steps to protect the national DNA registry in light of the allegations against Blake and separate revelations of problems in DNA analysis at the Houston police crime lab.

In Blake's case, 29 DNA samples that she placed into the database were removed and are being reanalyzed. The review so far has not found any instances in which her DNA analysis was inaccurate, and those samples have now been re-entered, Adams said.

In addition, FBI officials recently banned the Houston police lab from entering new DNA samples into the national registry. Judges in the Houston area have requested a grand jury investigation into that lab's practices.

The FBI made widespread changes in the mid-1990s after its lab was rocked by a whistleblower's allegations and an investigation that found shoddy science by several lab examiners. AP reported last month that Justice officials have identified about 3,000 cases that might have been affected by those earlier problems and have let prosecutors decide whether to notify convicted defendants.

The new problems surfaced in the last year.

FBI lab scientist Kathleen Lundy, an expert witness in murder trials who performs chemical comparisons of lead bullets, was indicted earlier this year on a charge of misdemeanor false swearing by Kentucky authorities after she acknowledged she knowingly gave false testimony in a 2002 pretrial hearing for a man accused of murdering a University of Kentucky football player.

Lundy informed her FBI superiors of the false testimony a couple of months after it occurred. By that time she had corrected her pretrial testimony at the trial and had been questioned about it by defense lawyers. Federal authorities decided not to prosecute her, but Kentucky prosecutors brought the misdemeanor charge.

In memos and a sworn affidavit, Lundy stated she had an opportunity to correct her erroneous testimony at the hearing, but didn't.

"I had to admit it was worse than being evasive or not correcting the record. It was simply not telling the truth," Lundy wrote in a memo to a superior.

"I cannot explain why I made the original error in my testimony ... nor why, knowing that the testimony was false, I failed to correct it at the time," Lundy wrote in a subsequent sworn affidavit. "I was stressed out by this case and work in general."

Lundy also disclosed she was increasingly concerned that a former lab colleague, retired metallurgist William Tobin, was beginning to appear as a defense witness in cases and openly questioning the FBI's science on gun lead.

"These challenges affected me a great deal, perhaps more than they should have. I also felt that there was ineffective support from the FBI to meet the challenges," Lundy wrote.

Lundy's written declarations have already been turned over in the Kentucky case and may have to be disclosed elsewhere where lead bullet analysis is being questioned.

In New York, state prosecutors cited the allegations when they dropped plans to call Lundy as a prosecution witness in a murder retrial. "Her value as a witness would be negated," New York City Assistant District Attorney James Rodriguez explained to the judge.

Adams, the lab director, said the FBI remains confident that its lead bullet analysis is based upon "a proper foundation" but nonetheless has asked the National Academy of Sciences to review the lab's work.

"We do anticipate some suggestions, ways to improve what we already do and we'll gladly look at that," Adams said. "We want correct and unassailable results and objective testimony, and to do that we've got to be open to outside scrutiny and outside review."

Tobin retired in 1998 as an FBI lab metallurgist after 27 years. He was part of the government team that concluded the TWA Flight 800 explosion over New York was caused by a mechanical problem, not a bomb or missile

In an interview, Tobin said he remains a staunch supporter of the FBI lab but long suspected while working alongside the bureau's lead bullet analysts that they were engaged in inaccurate science. After retiring, he said, he conducted research that substantiated his concerns.

Tobin said he also has gathered evidence that FBI lab experts are stretching their conclusions beyond lab reports when they reach the witness stand.

"Defense lawyers are being ambushed and jurors are being misled," he said. "There is no comprehensive or meaningful data whatsoever to support their analytical conclusions."