INDIANAPOLIS -- The Marion County Sheriff's Department is planning to crack down on sex offenders who don't regularly update their address information as required by law, RTV6's Jack Rinehart reported Tuesday.

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Indiana Sex and Violent Offender Directory

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The planning comes amid concerns that much of the information that authorities have for local sex offenders is incorrect. Indianapolis police, who maintain the local sex offender registry, say that nearly 500 of 1,672 registrants have ignored notices to update their registrations.

Sheriff Frank Anderson plans to announce on Friday measures to increase enforcement of registry laws, which require sex offenders to notify authorities of changes in address, employment status and education.

"We're going to do all that we can to be effective and proactive in making sure that the children of Marion County are safe," sheriff's Deputy Chief Herman Humbles said. "We will make sure that offenders are accountable."

A check conducted by RTV6 last month showed some entries on the local registry to be inaccurate. Out of 10 entries examined, only three could be verified. One offender had listed the address of a vacant lot, Rinehart reported.

Last month, few people were assigned to the list's verification. The sheriff's department had two reserve deputies who spent 10 hours a week trying to keep tabs on the registered offenders, Rinehart reported.