Tucson- It has been six months since Isabel Celis disappeared from her east side home. Her seventh birthday has come and gone and still no sign of her.

Her parents told investigators they last saw her before she went to bed on Friday, April 20th and reported her missing the next morning. A massive search ensued, one that made national headlines.

Tucson police reported receiving more than 1,000 tips but all came up empty.

As the months have gone by Rebecca and Sergio Celis continue to struggle with not knowing what happened to their daughter.

At this point they admit they have grown very frustrated with the investigation, one that has even cast suspicion over Sergio Celis. "I can't understand at the six month point how they have absolutely nothing, to have nothing, and if it was me, why wouldn't they have me gone already, I'm not afraid to say that", Celis said, "Even Becky (Rebecca Celis) says it to everyone, c'mon, when are we going to move on this, digging in the same hole. Can we get out there, because she is not here, in the first three days of the investigation of staying here, she's not here, she hasn't been here since the moment she has been gone from this house."

Rebecca Celis says they now have very little contact with the police and their frustration is reaching the breaking point, "Its very frustrating", she said, "it's hard to not know where the investigation is."

But a half a year later and the Celis' have not lost hope. Isabel's bedroom has been repainted and there's a new bike waiting. Rebecca Celis says she knows that one day her daughter will return, "I know that she is alive, I don't know how to explain it. She is alive, she is somewhere out there. and that I think that is a harder thing to find than a person who is not."

Right now there are two detectives working the case full time.

Tucson's police chief says if additional detectives are needed to act on a tip, they pull in additional resources, and agencies including the FBI, and U.S. Marshals.

If you have any information call 88-crime.