Tucson police investigators will return to areas around the home of Isabel Celis to question residents who may not have been interviewed earlier in the search for the missing girl, an official said Monday.

Police will leave a questionnaire at homes if they cannot immediately talk to residents, said Lt. Fabian Pacheco, a Tucson Police Department spokes- man.

Residents who get a questionnaire are asked to call in their answers to 88-CRIME. Tips about the case can be submitted online through the Police Department's website at tucsonaz.gov/police, Pacheco said during Monday's news briefing.

The questionnaire can be seen at azstarnet.com

During the monthlong investigation, police have received about 1,500 leads. Investigators have also questioned more than 540 registered sex offenders who live in the city and county.

Investigators plan to re-interview 257 Level 2 and Level 3 sex offenders whose crimes involved children age 10 and younger, Pacheco said.

It will be up to the fourth time some of the sex offenders have been questioned in connection with Isabel's disappearance.

The department is ending its regularly scheduled news briefings on the case, Pacheco said. Updates will be sent through emails to the media, and news conferences will be called as warranted, he said.

There is too little new information to provide the public in the search for Isabel, Pacheco said.

The 6-year-old was reported missing shortly after 8 a.m. April 21 from her midtown home in the 5600 block of East 12th Street.

Pacheco said much of the information investigators are gathering at this point in the case is too sensitive to share openly with the public.

The end of scheduled police updates is not an indication that the effort to find the missing girl has slowed, he said.

"We continue to explore every possible scenario in this case," Pacheco said.

He said Isabel's family continues to cooperate.

He added that court documents filed in the case will remain sealed at the request of investigators.

The 88-CRIME reward for information leading to an arrest in Isabel's disappearance is $50,500, and $49,500 is from private donations.

Contact reporter Carmen Duarte at 573-4104 or cduarte@azstarnet.com