PREACHER PREDATORS: INVESTIGATING CHILD SEX ABUSE IN THE PROTESTANT CHURCH -- JIM AVILA REPORTS ON ABC NEWS' "20/20," FRIDAY, APRIL 13

And: A Cardio-Free Diet� Too Good to Be True?

Plus: A Man Among Wolves -- Shaun Ellis Reflects on His Extraordinary Experience Raising Wolf Pups and Living Among the Pack

Child sex abuse by Catholic priests has been headline news in recent years, but is the same abuse happening within Protestant churches? In a six-month investigation, ABC News' "20/20" found preacher predators in every corner of the country, including several affiliated with the Southern Baptist Convention (SBC) -- the largest Protestant denomination. Jim Avila's exclusive report airs on "20/20," FRIDAY, APRIL 13 (10:00-11:00 p.m., ET), on the ABC Television Network.

Avila's reporting finds that the SBC -- an organization of 43,000 independent churches and 16.3 million members � has an overall structure that makes it difficult to police preacher predators. One example includes a profile of an SBC pastor who abused kids in Kentucky and then moved on to do the same to eight boys in Missouri, before he was finally sent to prison. In an interview with Avila, the SBC president concedes that there is a problem with tracking predators.

"20/20" lists numerous SBC preachers who have been convicted or charged with child sex abuse, including pastors still identified on the SBC's own website or ordained ministers. Avila also interviews a preacher who admits that, in his jobs as Southern Baptist preacher and teacher in East Texas, he molested more than 40 boys. For the first time, Ken Ward speaks publicly about how he manipulated families and churches as he targeted and molested children in his care, and how the church is actually a magnet for predators. "I wanted them to love me and that was part of the strategy," Ward tells Avila. He also gives insight to parents about how to spot a predator.

Also: What if a fitness expert said to kiss the treadmill goodbye � that the only way to lose weight and keep it off is to build muscle? Deborah Roberts reports on a controversial new book on weight loss, ABC News Now contributor Jim Karas' "The Cardio-Free Diet."

Plus: Shaun Ellis, founder of a wolf sanctuary at the Combe Martin Wildlife Park on England's southwest coast, gave up comfort, a family and the civilization that surrounded him to live with wolves. In 2004, when the lives of three pups at the sanctuary were at risk because their mother had stopped nursing them, Ellis decided to use years of knowledge he had accumulated to raise the captive pups himself by teaching them how to behave like wolves. He moved in with the young pack and assumed the role of tutor and leader -- the alpha wolf. "I was always drawn towards the animals more than I was a human society," Ellis said. The experiment was documented by a British television producer, Bernard Walton, whose footage will be broadcast next week on the National Geographic Channel. "What was extraordinary was the relationships that developed between the different wolves and Shaun," Walton said. "He had refined everything down to a fine art to be a wolf." Bob Brown reports.

"20/20" is anchored by Elizabeth Vargas and John Stossel. David Sloan is executive producer.