TUCSON, Ariz. â€"  Arizona's child welfare agency is prohibiting the father of a missing Tucson girl from having any contact with his other two children, but authorities say that doesn't mean he's a suspect in her disappearance.

Meanwhile Monday, police released transcripts of some of the 911 calls made after 6-year-old Isabel Mercedes Celis was discovered missing last month. In one of the calls, her father, Sergio Celis tells an operator that he believes "she was abducted from my house."

The dispatcher asks Celis why he thinks the girl was abducted.

"I have no idea," he said. "We woke up this morning and went to go get her up, start her baseball game and she's gone. I woke up my, my sons, I, we looked everywhere in the house and my oldest son noticed that her window was wide open and the screen was laying in the backyard. We've looked all around the house."

Police confirmed earlier Monday that the state's Child Protective Services agency has ordered Sergio Celis to stay away from his two sons, citing a need to ensure the boys' welfare. Neither police nor CPS officials would elaborate.

Tucson Police Chief Roberto Villasenor said at a news conference that Isabel's older brothers are "with their mother" and have "not been taken away" by CPS. He noted Sergio Celis is cooperating with the agency's order.

"He's voluntarily agreed with CPS to stay away from the children," Villansenor said. "We can't talk about other details."

Authorities added it's common for the agency to be involved in missing-child cases. They wouldn't say where Sergio Celis is living.

A message left for the father on his cellphone by The Associated Press was not immediately returned Monday, nor was a message left for his wife, Rebecca. Police said neither has an attorney.

Authorities have been searching for Isabel since she was reported missing the morning of April 21. They haven't identified any suspects in the case.

The Celises have said they last saw the girl in her bedroom the night of April 20. A window was later found open with the screen pushed aside in the family's home, police said.

Villasenor said Monday that investigators have determined Rebecca Celis had already gone to work April 21 when Sergio got up and discovered Isabel missing. The couple's sons also were at home, he said.

In one of the 911 calls, Sergio Celis tells an operator that he was watching a baseball game on television in the late night hours of April 20 "and I feel asleep and I never heard anything." He noted that he was on the other side of the wall from his daughter's bedroom.

Villasenor said police have processed more than 1,000 tips in their search and contacted more than 500 sex offenders living within the city limits.

"We have not eliminated any possibilities in this case," he said. "We're still doing a lot of work. It's a very painstaking process. I'm not giving up hope. Sometimes these cases are decided on one big break. We are waiting for that break."