A TEENAGE BOY FACING PRISON TIME FOR LOOKING AT SEXUALLY EXPLICIT WEBSITES - JIM AVILA WITH A CAUTIONARY TALE, FRIDAY, JANUARY 12 ON ABC

Plus: Was It Just a Hoax? -- Questioning the Identity of the Teenager Whose Autobiography Touched Millions of People; The Latest Diet to Help Keep the Annual New Year's Resolution to Lose Weight

A teenage boy looking at sexually explicit websites on the internet might sound like an innocent rite of passage. So why did 16-year-old Matthew Bandy, who admitted to looking at adult pornography - which is legal - end up facing 90 years in jail? Police said this Phoenix teen uploaded child pornography images to his home computer. Bandy said he never did such a thing. Senior Law and Justice Correspondent Jim Avila reports on a cautionary tale for both parents and kids - and anyone who uses the internet -- on "20/20," on FRIDAY, JANUARY 12 (10:00-11:00 p.m., ET), on the ABC Television Network.

And: Was an inspiring autobiography, A Rock and a Hard Place, written by Anthony Godby Johnson ("Tony") a tremendous hoax? "20/20" reveals new information as it revisits its report on the controversy surrounding Tony's identity. As the story goes, Tony wrote the autobiography after he was saved by social worker Vicki Johnson from a harrowing life in New York City, where he had been abused and forced into prostitution by his parents, and wound up with AIDS. Following the book's publication, the teen spent hours talking with friends and supporters over the phone, including San Francisco writer Armistead Maupin. Maupin thought he had been speaking on the phone with both the teen and his adoptive mother. He also says he received photos of Tony from Vicki Johnson. But after an early deal with HBO to turn A Rock and a Hard Place into a movie fell apart because no one from the studio was allowed to meet Tony, Maupin began to wonder whether the teen actually existed. He later turned his doubts into a fiction novel, The Night Listener.

"The mystery continues, and this is the longest running hoax, as far as I'm concerned, in literary history," Maupin tells Vargas. Tony's lawyer provided "20/20" with affidavits from his family and others swearing to have met Tony, and said Tony's medical and adoption records exist, but refused to send them due to privacy concerns. Elizabeth Vargas continues to explore the underlying mystery and has new information about the boy in the picture that Maupin says he received. Who is he?

Plus: It's an annual tradition, every bit as American as watching the ball drop in Times Square - the New Year's resolution to lose weight. From low-fat to high fiber to one-day detoxes and even three-week cleanses, is there anything we don't know about losing weight? Lynn Sherr reports on the newest weight loss book that touts losing weight is not about will power, it's about understanding the science. The authors, heart surgeon Dr. Mehmet Oz and internist Dr. Michael Roizen, describe their bestselling book You: On a Diet as the new biology of fat. "We're utterly failing as a nation, as a society, at losing weight. And you look at the details of that, it's because we don't really understand the biology of blubber," says Dr. Oz.

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