The wrongful incarcerations occurred more than 1,480 times in the last five years. They were the result of a variety of factors, including officials' overlooking fingerprint evidence and working off incomplete records.
FULL COVERAGE: Jails under scrutiny
Many of those wrongly held inside the county's lockups had the same names as criminals or had their identities stolen — problems that took days or weeks for authorities to sort out.
In one case, a mechanic held for nine days in 1989 on a warrant meant for someone else was detained again 20 years later on the same warrant. He was jailed for more than a month the second time before the error was discovered.
In another instance, a Nissan customer service supervisor was hauled by authorities from Tennessee to L.A. County on a local sex-crimes warrant meant for someone with a similar name.
In a third case, a former construction worker mistaken for a wanted drug offender said he was assaulted by inmates and ignored by jailers.
"I'm with criminals, and I was a criminal to them," said Jose Ventura, 53, who had never been arrested before.
The problems continue because of a breakdown not just by jail officials but by police who arrest the wrong people and by the courts, which have issued warrants that did not precisely identify the right people.
Sheriff's officials said they make every effort to avoid detaining the wrong suspects. They pointed out that the number of people wrongly identified as wanted criminals makes up a tiny fraction of the 15,000 inmates in the county's jails at any given time. The Sheriff's Department produced the tally of people who were jailed because of misidentification in response to a Times Public Records Act request.
The errors occur in jails up and down the state, and many of the misidentified inmates in the L.A. County sheriff's jails were arrested by law enforcement agencies outside the county.
In California, criminals are assigned a unique nine-digit number matched to their fingerprints. Some warrants issued by judges fail to include those identifiers, making it more difficult for police and jailers to determine whether they have the right suspect.
When those fingerprint numbers are included, police agencies sometimes fail to determine why the arrested person has a different number or no number at all. In those cases, authorities could catch the error by obtaining the wanted criminal's fingerprints from the state Department of Justice and comparing them with those of the person in custody.
"It's bureaucratic sloth and indifference," said attorney Donald W. Cook, who has represented more than a dozen clients mistakenly held on warrants issued for other people. "They don't want to take the heat for letting someone go who a cop has decided, no matter how tentatively, is the subject of a warrant."
Those mistakenly arrested told The Times that they were ignored when they pleaded with police and jail staff about their innocence. In the county jails, the Sheriff's Department has a policy to launch investigations when inmates protest during booking that they are not the wanted people. But records show the department conducted investigations for only a small fraction of the number of people who courts eventually ruled were not the right suspects.
Sheriff's officials said they are bombarded with false innocence claims from inmates. It would be impossible to check every claim, they said, and jailers' authority to release an inmate ordered detained by a judge is limited.
"People lie to us about who they are all the time," said sheriff's Cmdr. David Fender.
Victims of mistaken identification typically go through several rounds of checks before they land in L.A. County Jail. Arresting officers use the name, birth date and driver's license number of the person they stop to check for warrants. The first fingerprint check is usually done when officers bring the people they arrest to the police station where they are booked. From there, inmates are taken either to court or directly to county jail.