Isabel Celis: Missing Tucson Girl's Father Barred From Contact With Her Brothers

May 12, 2012— -- The father of missing Tucson 6-year-old Isabel Celis has been told by authorities he cannot have contact with the girl's two older brothers, who are now in the custody of their mother Rebecca, ABC News has learned.

A source close to the investigation said the development does not mean that investigators are turning their focus on Sergio Celis in the disappearance of his daughter. A police statement released Friday said it is "common practice for CPS [Child Protective Services] to become involved in investigations regarding missing children."

Calls to Sergio Celis and his wife -- who are no longer living together -- were not returned today. Other family members reached by phone refused to comment.

The police statement said new information regarding the welfare of the older Celis children led detectives to contact officials with Child Protective Services and call in Isabel's family for a meeting Friday. The statement did not specify what prompted the detectives and child welfare workers to take action.

"CPS instituted certain measures to ensure the continued welfare of the Celis children," the statement said.

A Tucson police spokesman, reached this evening, declined to provide additional details.

Isabel Celis was reported missing by her father around 8 a.m. April 21 after her mother left for work and her father went to wake her up.

The girl was not in her room, and a bedroom window was opened with the screen removed, police said.

The little girl was last seen around 11 p.m. April 20, when she was put to bed.

Police say they haven't eliminated anyone as a suspect, including the Celis family. They also haven't eliminated the possibility that investigators will find Isabel and bring her home safely, they say.

After Isabel was reported missing, police interviewed 15 registered sex offenders in the neighborhood.

Police have searched homes in the family's neighborhood, dug through a nearby landfull and searched waterways and drainage systems in Tucson. More than 1,000 tips have poured in regarding the six-year-old's disappearance, police said.

Isabel's parents made several public, emotional pleas for the safe return of their daughter in the days after her disappearance.

"Just please, please, to the person or persons who have Isabel, tell us what you want. We will do anything for her. We're looking for you, Isa," Sergio Celis said tearfully.

The search has also extended into Mexico, where authorities in the state of Sonora have been circulating photos of Isabel.