Officials pulled all cases handled by the lab tech after a sample review of 132 of them revealed she botched the evidence-collection process 20% of the time, police sources said.

"If there were, say, eight fingerprints on a given piece of evidence, she may have collected only three. Her work was sloppy. Finding the problems with the sample cases, it required a more thorough review," a police official said.

The bungled work - covering cases ranging from robbery to murder - may have allowed criminals to remain free, but seems unlikely to have falsely accused an innocent person, police said yesterday.

Still, defense attorneys said they want to know more. "We will be investigating this to see how it affects our clients," said Pat Bath a spokeswoman for the Legal Aid Society of New York.

"The common perception is that technology is always right, whether it is fingerprints or DNA, but this shows technology is only as good as the person who does the work," said Donna Lieberman, executive director of the New York Civil Liberties Union.

Top brass sent lists of the problematic cases to local precincts June 9 for investigators to pull records of cases handled by the lab tech, whose name has not been released.

Detectives were given until June 30 to collect data on any arrests, plea deals or convictions in the cases. The NYPD Central Investigation and Resource Division is reviewing the data on the 1,400 targeted cases.

The lab tech, who has 10 years experience in the department's vaunted Police Laboratory, was first flagged as a sloppy worker in October 2004.

She was transferred out of the fingerprint section in November 2004, after her bosses became aware she bowed to a request by a prosecutor to test a weapon for fingerprints a second time - even though by then the weapon had been handled by other police personnel.

After that foulup, which spurred the review, she was transferred to ballistics. She has since been moved to an area where she simply logs in evidence.