As the hunt continues for Isabel Celis, the 6-year-old Tucson girl who disappeared from her home April 21, new details about her home life are emerging. In December, several months before she was reported missing, Child Protective Services workers visited the home.

CPS representatives said they would not discuss the case and the reason they visited the Celis residence, reported the Arizona Daily Star. Tucson police spokesman Lt. Fabian Pacheco confirmed the department was made aware that protective services visited the home early on in the investigation.

The earlier case, we are aware of that, Pacheco said. I don't know if they were open or closed, but there were previous CPS contacts.

Tasya Peterson, a Child Protective Services spokeswoman, said officials would not comment about the previous case with the family.

The department has previously stated that it is working closely with the Tucson Police Department on the Celis case and we are not confirming, clarifying or correcting at this time due to the sensitive nature of this case and for the best interest of the children, Peterson wrote in an email to the Daily Star.

The disappearance of Isabel Celis has made national headlines. The search began for the 6-year-old when she was first reported missing on April 21, from her home in Tucson. The high-profile case has attracted the attention of people across the country as Tucson Police, the FBI, the U.S. Marshals and Mexican authorities search for her.

Police have received more than 1,000 tips during the investigation, but have been unable to identify a suspect. Police, however, stated they believe this is abduction.

We are not identifying any person or persons of interest, Pacheco said. We haven't narrowed it down to anyone in particular.

The police have not yet ruled out the parents, Sergio and Rebecca Celis, as potential suspects.

Recently, Sergio Celis reached an agreement with law enforcement officials that barred him from speaking with his two other children.

At a press conference on Monday, Tucson police discussed the decision to prevent Sergio Celis from having contact with his two sons, who are 10 and 14. While they did decline to provide any relevant information for the decision, they said it should not be taken to mean he is a suspect in the case.

A voluntary agreement was reached between Child Protective Services and the parents to restrict access or, voluntarily, for Sergio to give some space and distance away from the two older children, Chief Roberto Villasenor said.

Police said they developed new information regarding the welfare of the children.

This does not mean we have settled on a path in this investigation, the chief said, reported the Daily Beast.

However, police did not specifically say they ruled out the parents as suspects and are looking at many scenarios. Villasenor conceded that their relationship with the family is somewhat more strained because the family members have not been ruled out as suspects.

We are doing more interviews and are asking more pointed questions, he added, reported the Daily Beast.

Since she has been missing, police have received thousands of tips and estimate they spent almost $1 million searching for Isabel. Isabel's parents have made several public appeals for her safe return.

Every day makes us a little more worried, Villasenor said, but I'm not going to give up hope.

Police also recently released 911 calls of the day Isabel was reported missing.

In the audio recording, Isabel's father, Sergio Celis, calmly talks to the 911 operator before being transferred to police.

I want to report a missing person, he said April 21, reported ABC. My little girl, who is 6 years old. I believe she was abducted from our house.

The operator then asks Celis why he thinks his daughter was taken.

I have no idea, he said, reported Reuters. We woke up this morning ... and she's gone. I woke up 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.

The operator then asks where the mother is. Celis said that she went to work, but he informed her of the situation.

I just called her to get her butt home, he said with a laugh.

Another emergency phone call was placed by Isabel's 14-year-ol brother, Sergio, who gives the phone to his mother Rebecca. Both are frantic and worried on the phone.

I went to work at seven this morning ... and she is five, six, could you please hurry and get someone over here, she said, as she begins to cry.

However, Rebecca begins to compose herself when the emergency operator asks for specific information regarding her missing daughter, reported ABC.