-- Virginia has begun a review of DNA evidence used in at least 160 cases by the state's Division of Forensic Science following a study critical of the crime laboratory.

Robert J. Humphreys, a Virginia Court of Appeals judge, is leading the effort, which will review evidence in cases that date from 1994. About two dozen are death row cases, and the analysis marks the first time a state has volunteered to revisit the cases of executed felons on a large scale.

One case involves Robin Lovitt, an inmate on death row who is scheduled to be executed July 11. State officials have said that other evidence was used to convict Lovitt and that his fate will not be affected by Humphreys's review. Emily Lucier, a spokeswoman for Attorney General Judith W. Jagdmann, said the office does not consider Lovitt's conviction a DNA case.

The audit that led to the review criticized the Virginia lab's role in the case of Earl Washington Jr., a former death row inmate who spent 17 years in prison before he was pardoned in 2000. DNA evidence was not gathered for Washington's conviction, but it was used later to determine his innocence.

In its study, the American Society of Crime Laboratory Directors concluded that a chief scientist failed to follow proper procedure when testing a piece of evidence in Washington's case and that his analysis of that evidence was wrong.

The auditors also concluded that an internal review failed to properly identify the errors made by the scientist, Jeffrey Ban.

Humphreys's team of half a dozen national forensics experts began its research last week. The analysis stops short of actually testing or retesting DNA. Instead, experts will determine whether scientists who handled the evidence followed proper procedures. The review should take about eight weeks.

"You need to have impeccable credentials to go into court," said Del. David B. Albo (R-Fairfax), a member of the House Courts of Justice Committee and co-chairman of the Virginia State Crime Commission. "If they can't show that tests were done properly, that hurts prosecuting crimes."

The General Assembly enacted a law this year that makes the Division of Forensic Science, which runs the crime lab, an independent state agency and creates an advisory board to help oversee its work. Several criminal defense lawyers have said that the changes were inadequate because they did not create a watchdog department to review the lab's reports and conclusions.

Humphreys did not respond to phone messages left at his offices in Hampton Roads and Richmond.

Although the audit did not uncover any systemic problems at the lab, a spokeswoman for Gov. Mark R. Warner (D) said the review could restore confidence in one of the nation's most respected crime laboratories and lead to changes in laboratory policy.

"Even in this review, we've sought to have a very independent process," said Ellen Qualls, Warner's director of communications, adding that three cases from each examiner in the department will be reviewed. "At every step of the way, Virginia has sought to go above and beyond what was requested."

Legal experts said the review must determine whether the Earl Washington case was an isolated incident or an example of long-standing problems within the lab.

A successful analysis by the investigators "would look at the errors that happened in the Earl Washington case and determine the source of those errors and figure out whether they are systemic," said Betty Layne DesPortes, a criminal defense lawyer in Richmond who heads a legal panel for the American Academy of Forensic Science.

"One of the overriding themes of the errors was a lack of strict adherence to scientific protocol. A full investigation of the errors is crucial to maintain our integrity in the results," she said.

She added that so far, she has been impressed by the methodology and approach Humphreys has taken with the review.

The review will include not only all death row cases since 1994 that hung on DNA evidence but also more routine testing done by Ban and others, state officials said.