LOS ANGELES (CBS) —  A Massachusetts man was sentenced Thursday to 20 years behind bars for masquerading as a teenage boy to lure underage girls into posing for sexually explicit videos that he then posted online or shared with others.

Lawrence Joseph Silipigni, 42, pleaded guilty in December in Los Angeles federal court to using a computer to induce a minor to engage in criminal sexual activity, and to production of child pornography.

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Many of his victims lived in the Southland.

“This wasn’t just a guy on a computer,” Assistant U.S. Attorney Terrence Mann told the court. “This was someone whose behavior was getting increasingly dangerous.”

U.S. District Judge Otis D. Wright II called Silipigni “an extreme danger to the community” and, along with the 240-month prison term, ordered him to undergo supervised release for life, register as a sex offender, and pay restitution of $2,800 to one of his four named victims.

Prosecutors said Silipigni stole the MySpace screen name of a boy named “Jamie” and used his photos to entice underage girls into engaging in sex chats, removing their clothes and masturbating in front of a webcam.

Silipigni was named as a suspect after a 14-year-old Southern California girl reported she was contacted online by a man posing as a teenage boy in 2007. The girl told authorities that over six months, Silipigni persuaded her to perform for him in a sexually graphic manner via her webcam, according to the FBI.

“As a final act of betrayal” with potentially “devastating lifelong effects,” Silipigni uploaded a 22-minute excerpt of the video on the Internet that showed the girl’s face and body, Wright said.

The judge quoted from the girl’s victim impact statement: “I’m scared something bad will happen to me because of this. I feel like my whole future could be ruined because of what the defendant did to me.”

Mann added that the victim will have to wonder for the rest of her life if people she is first meeting might have seen the video and recognize her.

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The corpulent Silipigni, the father himself of two pre-teen girls, wore a green jail-issued windbreaker, shackles and handcuffs. He cried as he apologized as his father, brother and sobbing wife looked on.

“What I did to those teenage girls was totally uncalled for,” he said. “I had a compulsion I hid from everyone. I’m so ashamed for what I did.”

Referring to his own daughters, he added, “I’m afraid they’re gonna meet someone like me some day — and I won’t be there to protect them.”

According to the FBI, Silipigni shared the videos he made, along with other child pornography, with a network of men engaging in the same activities.

When federal agents arrested Silipigni at his Saugus, Mass., home last year, they reported finding more than 100 videotapes of webcam sessions involving teenage girls.

Prosecutors said Silipigni threatened to notify victims’ parents if they stopped communicating with him after learning his true age and identity, and if they did not comply with his requests.

On at least one occasion, Silipigni met a minor victim in person.

According to court papers, FBI agents spoke with a 15-year-old Massachusetts girl who acknowledged exposing herself to Silipigni via webcam, thinking he was “Jamie.” Investigators believe Silipigni contacted numerous underage girls, court papers show.

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