California has lost track of more than 33,000 convicted sex offenders, despite a law requiring rapists and child molesters to register each year for inclusion in the Megan's Law database.
"We don't know where they are," said Margaret Moore, who until recently ran California's sex offender registry.
Sex offenders are not checking in with law enforcement, which in most cases is a felony. And many overworked police departments are not following up.
"We're expecting sex offenders to be reporting their addresses and that's the problem," said Laura Ahearn, executive director of Parents for Megan's Law, a national victims' rights group.
After repeated requests last year, the state Department of Justice provided Associated Press with numbers on every ex-convict who showed up in California's sex registry from 1946 to Nov. 27, 2002.
The data show that the state does not know the whereabouts of at least 33,296 sex offenders, or 44% of the 76,350 who registered at least once. Many of those ex-convicts haven't been heard from since.
Failing to register could put high-risk offenders in jail for up to three more years, but most police departments are not enforcing the law.
No one knows how many of the missing sex offenders have struck again. But nationally, 52% of rapists are arrested for new crimes within three years of leaving prison, according to the U.S. Justice Department.
Among those missing is Richard Flick, who was convicted of molesting four children in the 1980s and '90s. Flick was freed from Atascadero State Hospital in 1999 despite warnings from the hospital staff that he had not resolved his sexual attraction to children.
Even he said that it would be "disastrous" to be released without supervision. "I'd be a fool to walk out there on my own," he said.
The data provided to AP show that 27,577 sex offenders are "out of compliance," meaning that they haven't registered in at least a year.
An additional 5,719 "cannot be accurately categorized" -- of these, most have not been heard from since 1995, said Norm Pierce, manager of the department's Violent Crime Information Center, which oversees the database.
Atty. Gen. Bill Lockyer acknowledged that changes are needed.
"Our system is inadequate, woefully inadequate," he said. "It can only be improved by putting money into the local law enforcement agencies. It's a matter of resources."