The fate of little Isabel Celis was unknown for five years after the 6-year-old Arizona child disappeared from her bed in Tucson — until her remains were found in a desert grave last year. With the arrest of a convicted sex offender, the family know has answers about why the child vanished. The family of another murdered Tuscon girl – Maribel Gonzales — also knows what happened to the 13-year-old in 2014.

Christopher Matthew Clements, 36, is charged with killing both children. Nancy Grace looks at how the system may have failed these families as the suspect was allowed to walk free in their neighborhood despite a long rap sheet of crimes. Her experts in this episode include victim’s advocate Marc Klaas — founder of Klass Kids Foundation, New York psychologist Caryn Stark, forensics expert Joseph Scott Morgan, Atlanta juvenile judge & lawyer Ashley Willcott, and CrimeOnline.com reporter Jennifer Dzikowski.

Finally, answers in the disappearance, murder of 6-year-old Isabella Celis

“Crime Stories with Nancy Grace” is also a national radio show heard on SiriusXM channel 111 airing for two hours daily starting at 12 p.m. ET and around the country on local radio stations. You can also subscribe and download the daily podcasts at iTunes and Google Play.

[Feature Photo: Isabel Celis; Maribel Gonzales/Handout]