Isabel Mercedes Celis Case: Police to re-interview sex offenders in search for missing Ariz. girl

(CBS/KPHO) TUCSON, Ariz. - Tucsan police say they plan to re-interview registered sex offenders in the case of missing 6-year-old Arizona girl Isabel Mercedes Celis.

Pictures: 6-year-old vanishes from Arizona home

Police said at a Monday afternoon news briefing that detectives will target those offenders known to abuse children under 10-years-old, CBS affiliate KPHO reports.

Police have reportedly already spoken to 540 registered sex offenders in connection with the girl's disappearance.

Authorities have been searching for Isabel since her father, Sergio Celis, reported her missing April 21. Police haven't determined whether Isabel was abducted by a stranger or someone the family knew.

Police said they also plan to canvass 30 to 40 homes in neighborhoods near where the girl lives, KPHO reports.

Complete coverage of Isabel Mercedes Celis on Crimesider