Isabel Mercedes Celis Case: Child welfare workers went to missing Ariz. girl's home last year

(CBS/AP) TUCSON, Ariz. - Police investigating the disappearance of 6-year-old Isabel Mercedes Celis from her family's southern Arizona home say child welfare workers went to the household in December.

Pictures: 6-year-old vanishes from Arizona home

The disclosure comes nearly a week after Sergio Celis, Isabel's father, was barred from having any contact with his 10- and 14-year-old sons.

A Tucson police spokeswoman confirmed the visit but says she couldn't describe the circumstances that prompted it. According to CBS affiliate KOLD, Tucson Police Sgt. Maria Hawke said it would be inappropriate to comment further because police had not been involved in the visit.

A state child welfare agency spokeswoman declined to confirm the visit to the Associated Press.

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

Complete coverage of Isabel Mercedes Celis on Crimesider