LANSING, Mich. (AP) - A 15-day address verification period for Michigan sex offenders is underway. It started on Wednesday. During the period, state law requires all registered offenders to report in person to their local law enforcement agency, sheriff's office or nearest Michigan State Police post to verify their address. Tier 1 offenders must verify their address annually, during the first 15 days of January. Tier 2 offenders must verify their address semi-annually, during the first 15 days of January and July. Tier 3 offenders must verify their address quarterly, during the first 15 days of January, April, July and October. Failure to do so carries a penalty of up to two years behind bars. Thumb area residents verifying at State Police posts are asked to visit the Caro or Lapeer post.