A fourth teenager was arrested Monday in the beating of a girl that was recorded on video camera and broadcast on the Internet, police said.

The 16-year-old North Babylon boy, who recorded the Dec. 18 beating of a 13-year-old girl by three other girls, surrendered to police Monday afternoon and was charged with unlawful assembly, Suffolk County police said.

He was released on $100 station house bail and was told to appear in court March 22.

VIDEO: Teens Post Shocking Beat Down Video on Web

Earlier this month police arrested two 14-year-old girls and a 13-year-old girl on charges of juvenile delinquency and attempted assault in the beating at a high school.

The video was shown on Web sites including YouTube and MySpace, which are popular with young people.

On Monday, Suffolk County Executive Steve Levy said he hoped the boy's arrest would send a message to youths.

"I hope this arrest, which we expect to be the final arrest in this case, makes it clear that we are taking this abhorrent behavior very seriously," Levy said in a statement.

He said he hoped young people would get the message "that bullying or physically abusing peers is serious and unacceptable, not entertainment fodder for a Web site."

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