"They allowed them to search, but a very cursory search," Darien Biggs said. "They didn't search the area and they didn't search his vehicle."
Blalock has denied any involvement in Mikelle's disappearance, and although police describe him as a promising lead, he is not an official suspect. He was sentenced to 187 years in prison for his attack on Quinnett.
Quinnett was so convinced that he took Mikelle that she offered to drop all charges against him if he would confess to taking the little girl.
She also contacted the Biggses to share her suspicions, telling Tracy, "He was their closure. He was the answer."
The Biggses began writing Blalock in prison in a desperate attempt to find out what happened to their daughter.
In his letters, Darien Biggs asked him directly, "Did you do it?"
Blalock answered their correspondence, writing that he needed to "make things right with you and your family."
Blalock agreed to a visit with the grieving parents.
"I was nervous," remembered Tracy Biggs.
But she was determined to look him in his eyes to decide whether or not he was guilty.
"He just denied, denied, denied," said Darien Biggs.
But after speaking to Blalock through a glass wall for 90 minutes, Tracy and Darien Biggs thought they had found their daughter's killer.
"His movements ... his jitteriness ... he couldn't look you straight in the eye -- just things ... that would indicate that he was lying," Tracy Biggs said.
But the case remains unsolved, and the Biggses do not yet know what really happened to their daughter.
In the meantime, they struggle with living a life of unknowns.
"I'm going to live another 40 or 50 years and just ... never know -- ever? That's what my life is?" asked Darien Biggs. "I don't think I'll ever be complete without knowing."
If you have information that might help solve the mystery of what happened to Mikelle Biggs, please contact the Arizona Police Department on their website, http://mesaaz.gov/police/, or by phone (480) 644-2211.