'20/20' HAS FIRST INTERVIEW WITH PARENTS OF SHANANN WATTS AFTER HER HUSBAND, CHRIS WATTS, PLED GUILTY TO MURDERING SHANANN AND THEIR TWO YOUNG DAUGHTERS

Hour Includes Exclusive Interviews With Neighbor and Friends of Shanann

'20/20' Airs Friday, Dec. 7 (10:01 - 11:00 p.m. EST), on ABC

"20/20" features an exclusive interview with Frank and Sandra Rzucek, Shanann Watts' parents.

Christopher Watts was sentenced to life in prison without parole for murdering his pregnant wife, Shanann, and young daughters Bella and Celeste in Colorado. "20/20" co-anchor Amy Robach sits down for the first interview with Shanann's parents, Frank and Sandra Rzucek, who open up about their daughter, granddaughters and their grief. The pair also discusses their relationship with Chris and the shocking crime that devastated their family. The hour features exclusive interviews with neighbor Nathan Trinastich and Shanann's friends Cassandra Rosenberg and Cristina Meacham. "20/20" airs Friday, Dec. 7 (10:01 - 11:00 p.m. EST), on ABC.

"20/20" includes interviews with Nickole Atkinson, Shanann's friend who first reported her missing; Michael Rourke, Weld County District Attorney; and John Camper, director of the Colorado Bureau of Investigation. The hour also features new videos, documents, photos and texts from the case, coupled with newly released police evidence, in an attempt to explore the question of why Chris committed the murders.

Following the disappearance of 34-year-old Shanann, 4-year-old Bella and 3-year-old Celeste, Chris Watts appeared to be a distraught husband and father, longing for his family to return home. However, Chris quickly became the prime suspect. Authorities claim that his motivation stemmed partially from his desire to start a completely new life without his wife and children but instead with a new woman, Nichol Kessinger, with whom he was having an affair. Nichol says Chris had told her he was in the process of divorcing Shanann. Prosecutors say that Chris strangled Shanann and smothered his daughters Bella and Celeste to death. He later dumped the bodies of the children in oil tanks and buried his wife in a nearby shallow grave. Chris pled guilty to murdering all three.

"20/20" is anchored by David Muir and Amy Robach. David Sloan is senior executive producer.