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ST. LOUIS — Police don't know the whereabouts of nearly 1,300 registered sex offenders in Missouri, including hundreds who fall into the most dangerous category, according to state audit released Monday.

Missouri law requires convicted sex offenders to register their names, addresses and other information with their county law enforcement, most often the sheriff's department. The Missouri State Highway Patrol maintains a publicly available database. Offenders must keep their information up-to-date and notify law enforcement when they move.

The audit released by state Auditor Nicole Galloway says 1,259 sex offenders are unaccounted for — about 8 percent of the nearly 16,000 registered sex offenders in Missouri — and it blames inadequate enforcement of the registration requirement at the local level. In 14 counties and the city of St. Louis, the whereabouts of more than 10 percent of sex offenders is unknown.

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Galloway said the findings are troubling.

"The law requiring sex offenders to register has been on the books for more than 20 years to help keep our communities, and especially our children, safe," Galloway said in a statement. "But if the law isn't enforced, it's not effective and public safety is compromised."

The law took effect in 1995 and was updated this year to classify sex offenders into three tiers. The most dangerous sex offenders are listed in Tier III for offenses that include rape, sodomy or first- or second-degree child molestation. Those offenders must register with local police every 90 days for the rest of their lives.

Galloway said the audit found that at least 794 of the non-compliant offenders met the criteria for Tier III.

Failure to comply with registration requirements is a felony. The audit found that less than 10 percent of noncompliant offenders had an active arrest warrant against them.

In addition to urging strong control at the local level, the audit cites a need for the highway patrol to improve procedures for maintaining the database and for helping local police enforce registration requirements.

Galloway also encouraged the Legislature to strengthen the state law to require background checks for school volunteers, and to allow her office to access all court records.