Late on the morning of April 14, 2006, a troubling letter rolled off the fax machine in the harried, disordered fingerprint unit of the Los Angeles Police Department.
Months before, one of the unit's print specialists had determined that several prints lifted from a cellphone store where a burglary had occurred belonged to Maria Maldonado, a 25-year-old hospital technician. Two others in the unit had signed off on the work. The match had given authorities the evidence they needed to arrest the woman and charge her with the crime. When the case went before a judge, however, a renowned fingerprint expert testified that the police had made a mistake.
The district attorney's office sent the fax demanding answers.
The analysts stood by their work, but days later the file containing the suspected burglar's prints mysteriously disappeared from the unlocked drawer where it was kept. Working from copies of the prints, others in the unit and outside consultants later concluded that Maldonado had, in fact, been wrongly accused, and the charges were dropped.
The case offers a stark profile of a high-stakes operation that for years has been marred by inadequate training, antiquated facilities, poor supervision, careless handling of evidence and other shortfalls, according to internal police records and interviews.
"We were trying to hold on by the skin of our teeth to make sure things were done right," said Diana Castro, the latent print unit supervisor who retired early last year. "Were we perfect? No. Did we do everything right? No. We did what we could to keep the cases flowing -- to assist the detectives and the community."
As focus in law enforcement has turned increasingly to the promise of DNA analysis to solve crimes, the fingerprint unit has languished as a neglected but heavily used cornerstone of the LAPD. It operates 24 hours a day, seven days a week, with about 80 forensic print specialists rotating through three shifts.
They are summoned by detectives to roughly 24,000 crime scenes every year and about 60% of the time are able to collect fingerprints.
Prints are scanned into automated databases that generate dozens of possible matches to known people. Specialists then seek a more precise match by comparing the prints under a magnifying glass, looking at the distinct ways in which the ridges of skin that make up a fingerprint split, stop and loop. Conclusive matches are made about 3,500 times a year.
