Missing Tucson Girl Isabel Celis' Family Will 'Never Give Up Finding Her' K-9 search for Isabel Mercedes Celis indicate a "hit" in the girl's home.

April 23, 2012 -- Relatives of Isabel Mercedes Celis, a 6-year-old girl who went missing from her Tucson, Ariz., bedroom over the weekend, say they will "never give up" in their efforts to track her down.

"We appreciate everyone's interest in finding our daughter, Isabel, and thank all the volunteers who have come out to search for her," the family said in a statement read by the Tucson Police Department.

"We are cooperating fully with authorities and are focused only on her safe return," the statement said. "We appreciate all your energy and efforts and continue to need the community's help. Please call the TPD if you have any information. We love Isabel and will never give up finding her. Thank you for all your support."

Tucson police searched the homes of a number of residences today close to where Isabel disappeared, including one home on the same street as the girl's house.

The search entered day three today with investigators combing a nearby landfill, canvassing the neighborhood interviewing residents, and examining evidence that FBI search dogs "hit" in the Celis family home.

Celis was reported missing by her father around 8 a.m. Saturday after Celis' mother left for work and her father went to wake her up. The child was not in her room, and a bedroom window was opened with the screen removed, Villasenor said.

The little girl was last seen around 11 p.m. Friday, when she was put to bed, he said.

Villasenor would not say which residences were searched today, after police obtained warrants for the case, but did acknowledge that more than 15 registered sex offenders live within a three mile radius of the family's home, including at least one who lives in the immediate vicinity.

Detectives have interviewed all of the offenders, he said.

The search for Celis intensified after two FBI search dogs hit upon something in the Celis family home overnight. Villasenor noted that there was a cadavaer dog and a scent dog used in the search.

"We have information we obtained from the dogs that has necessitated more follow-up investigation," Tucson Police Chief Roberto Villasenor said today.

Police evacuated the Celis family from their home today following the dog search, which involved one cadaver dog and one scent-following dog, Villasenor said. They are treating the house as a crime scene.

Police have not ruled out the parents of the missing child as suspects.

"We are investigating all of the parties involved," he said today.

Investigators also continued to search a nearby landfill today where garbage was taken after being picked up at the Celis's home on Saturday, Villasenor said. Having police turn to a landfill for evidence of the girl was a grim turn in the investigation.

Celis' uncle, Justin Mastromarino, told ABC News that the girl's mother is devastated over the disappearance of her "sweet little girl."

"They're very upset right now, mother is beside herself. We're just trying to let police do their thing and get as much info as possible," said Mastromarino.

Mastromarino said her family is a loving one.

Ground and air searches for the girl will continue today. More than 250 people have helped search the area around the Celis' Tucson neighborhood this weekend, including canvassing neighbors to ask about any possible leads.

"We don't have an actual piece of evidence that points us in one direction or another, so, for example we don't have a piece of evidence that says she was definitively taken from the residence," police spokeswoman Sgt. Maria Hawke said. "We don't have any specific piece of evidence that tells us she left the residence on her own."

Celis' family told ABC News on Sunday that they have no doubt she was kidnapped by a stranger.

"You don't think anything like that would actually really happen to you. And all of sudden, you wake up one morning and you're in that scenario. Everything goes through your mind, you're angry, you're upset, you're frustrated, you're confused," Mastromarino said.

ABC News' Michael S. James contributed to this report.