TUCSON - On day 13 of the investigation, 40 to 50 Tucson Police officers and detectives are still assigned to the disappearance of 6-year-old Isabel Celis.

She began the conference with a clarification about what yesterday's activity at the Celis house was about.

"As you all know, the family has been allowed to return to the house," Hawke said. "They can come and go as they please. It's my understanding that they are not staying there yet. That may come in the future. I simply don't know, ultimately that will be their decision. They were happy to cooperate with investigators as they have been all along - to help us get that better understanding, that was what yesterday was all about."

"The budget is not a concern, really, the key concern is getting Isabel home safely," Tucson Police spokesperson Sgt. Maria Hawke told the media during the department's 2 p.m. daily news conference.

Sgt. Hawke confirmed that both Sergio Celis and Rebecca Celis have taken polygraph tests, but TPD is not releasing the results, as the investigation is still ongoing at this time.

She said the number of tips they have received so far remains at about 500, and she reiterated that they are working this case with the belief that they will bring Isabel home alive and safe.