TUSCON, Ariz. (OLD/CBS) -- Six months ago today, Sergio and Becky Celis' world was turned upside down when their daughter Isabel vanished.

"Knowing that it's been already half a year that our baby's been gone, yes it's overwhelming," said Sergio Celis.

But each day they become more hopeful. "We're waiting for her, we're ready," said Becky Celis, "So that's what gets us by."

They've spruced up her room painting the walls purple. Cards and stuffed animals sit on top of her bed and a small memorial off to the side on her nightstand. For the past six months, Isabel's family has prayed every day for her safe return.

We've learned Sergio's sister hired a private investigators during the Summer and police tell us they've gotten around three thousand leads and have two detectives actively working the case. But, Isabel's parents say they're not satisfied.

"I'm sorry to have to say this but we feel like we've been blown off," said Sergio.

Sergio and Becky had no problem speaking with us today but six months ago it was a different story. It took them days before making their first appearance to the media. Many have pointed the finger at Sergio.

Matt Mendes: "You know there are still a lot of people who think you have something to do with Isabel's disappearance?" Sergio: "Let them think what they want."

The family says critics are the least of their worries. "We are here living the nightmare. There's a lot more eating away at our hearts," said Sergio.

They believe the truth will come out eventually. Until then, they maintain their focus on finding Isabel.

Becky had this message to anyone with information on Isabel's whereabouts. "I pray you have the courage to come out and have the courage to be Isabel's angel and bring her home," said Becky.