STATE COLLEGE, Pa. (AP) -- The son of former Penn State assistant football coach Jerry Sandusky participated in a documentary about his father's sexual-abuse case and hopes to become an advocate for child victims.

Matt Sandusky told the Centre Daily Times that he took part in "Happy Valley" because he has become strong enough to tell his story and wants to speak out to help other survivors. The 100-minute film, debuting this week at the Sundance Film Festival, explores whether it was an open secret that Sandusky was molesting boys.

"For me and all survivors it is important to have control over the timing and setting of (the) disclosure," Matt Sandusky told the newspaper.

Sandusky had been listed as a defense witness at his father's 2012 trial, but he instead disclosed through lawyers that he had also been abused and didn't take the stand. Jerry Sandusky, convicted on 45 counts involving 10 boys, maintains his innocence and is appealing his conviction. He is serving a 30- to 60-year prison term.

Matt Sandusky declined to elaborate on his comments in the film, but he said he discusses his childhood, the abuse and his relationship with family. He is one of six children adopted by Jerry and Dottie Sandusky. He petitioned last year to legally change his name, and that of his wife and four children.

"I hope that people will begin to understand what I have gone through," he told the newspaper. "My role in the film was to share the perspective of a survivor, to give survivors a voice."

An online trailer advertises the film, made by "The Tillman Story" director Amir Bar-Lev, as a "complicated and tragic tale." Matt Sandusky watched the film in a recent private screening.

The film, which debuted Sunday, has a few more Sundance screenings scheduled this week. It's not yet clear if or when it will come to Pennsylvania.

Matt Sandusky praised the victims who went public.

2014 Variety Media, LLC, a subsidiary of Penske Business Media; Distributed by Tribune Content Agency, LLC