Tucson Police say they are now working with Child Protective Services in the investigation of missing 6-year-old Isabel Celis who was last seen at her home three weeks ago.

Tucson Police Sgt. Maria Hawke said detectives recently became aware of information regarding the welfare of the older Celis children.

Tucson police said the information was given to CPS for their consideration relating to police's investigation of Isabel's disappearance. TPD says CPS has "instituted certain measures to ensure the continued welfare of the Celis children." At this point, police will not elaborate on what those measures may be.

On Friday, CPS released this statement to the media.

"The Department can confirm that CPS is working closely with law enforcement to ensure the continued safety of the children. At the present time, the children are not in CPS custody. The Department appreciates the community's support and understanding in protecting the privacy rights and safety needs for these children during this ongoing joint investigation."

Police confirm Isabel's two older brothers are now in the custody of one parent and the other parent is not allowed to see them. Though, TPD will not not say which parent has custody

Investigators say they are still working through 1,000 tips that have poured in from the community since Isabel was last seen in her bedroom the night of April 20. Her father discovered her missing the next morning.

Police say they have not identified any suspects, though, they have not ruled anyone out at this point.

Anyone with information is urged to call 9-1-1 or 8-8 Crime.