The once-troubled St. Paul police Forensic Services Unit has won international accreditation, police officials announced Wednesday.

The accreditation, from the ANSI-ASQ National Accreditation Board, "signifies that the unit meets or exceeds" international standards.

The crime lab came under fire in 2012 after two public defenders challenged its scientific credibility in several drug cases. Subsequent audits found widespread problems, including poor staff skills, poorly maintained testing instruments and illegible lab reports.

The city of St. Paul spent $1 million to upgrade equipment and lab space and make improvements in the unit, located on the third floor of the police department's main offices at the east edge of downtown. The unit now has more forensic lights, new cameras and two high-tech tools for collecting fingerprints: cyanoacrylate fuming chambers and a Reflective Ultra Violet Imaging System.

The Forensics Services Unit collects evidence, photographs and documents crime scenes, conducts blood testing, collects DNA and does other analysis to help solve crimes.

St. Paul police continue to work with the Minnesota Bureau of Criminal Apprehension on DNA analysis, drug testing and firearms testing.

The unit is now managed by a certified latent print examiner and forensic lab manager. Its staff includes two police sergeants and five officers and a civilian forensics scientist, said Steve Linders, a St. Paul Police spokesman. The unit is looking to hire three or four more civilian employees, including a quality assurance person.

"This accomplishment is a testament to the exceptional work of our lab manager and our lab staff," said Assistant Police Chief Kathy Wuorinen, who oversees the unit. "They have worked diligently to ensure that our lab meets the highest standards of operation — and they achieved accreditation sooner than expected. The public can have complete confidence that our lab provides the highest level of service and precision that comes from merging the worlds of law enforcement and science."

James Walsh • 651-925-5041