Los Angeles police have acknowledged that innocent people have been arrested due to faulty fingerprint analysis.
Police say they do not know how many other people may have been falsely accused because of the problems.
Rhonda Sims-Lewis, chief of the Police Department's technical bureau, says changes have since been made to procedures in the department's Latent Print Unit.
The internal report blames shoddy work and poor oversight for the mistakes.
According to the Los Angeles Times, who obtained a 10-page internal report, Los Angeles Police officials don't know how many other people might have been wrongly accused over the years.
The report highlighted two cases in which criminal defendants had charges against them dropped after problems with the fingerprint analysis were revealed.
"This is something of extraordinary concern," said Michael Judge, public defender for Los Angeles County, in a statement to the Los Angeles Times. "Juries tend to accord the highest level of confidence to fingerprint evidence. This is the type of thing that easily could lead to innocent people being convicted."