TRI-STATES -- Law enforcement throughout the Tri-States will be spending Halloween night checking on sex offenders to make sure they're following the law.

Missouri's law requires all sex offenders to keep their lights off and post signs stating that they have no candy or treats.

They also must stay home from 5 to 10:30 this evening.

Police suggest mapping out your trick-or-treating route to avoid sex offenders ahead of time.

Here are some links to sex offender websites in your state.

Family Watch Dog

Illinois State Police 

Missouri Highway Patrol

Iowa Sex Offender Registry