Dharun Ravi is accused of using a webcam to video tape Tyler Clementi and then posting it online.
Clementi later committed suicide after discovering he was being watched.
The case is about whether Dharun Ravi was staging a prank or a hate crime when he set up a webcam to spy on his roommate Tyler Clementi, who committed suicide by jumping off the George Washington Bridge days later.
"This was not a prank, accident, or in good nature," said Prosecutor Julie McClure.
In opening statements Friday morning, the prosecutor described Rhavi's behavior, which included numerous messages on Twitter inviting followers to watch an intimate encounter between the 18 year old Clementi and another man.
"I turned on my webcam and saw my roommate making out with a dude. It was like opening the blinds in the room," the Prosecutor said, repeating Ravi's statement.
In a 15-count indictment, Ravi is charged with a range of crimes, most serious, a hate crime: bias intimidation.
Bullying Clementi for being gay, Ravi could face a 10 year sentence.
A Rutgers University student who says she saw a webcast of a classmate's intimate encounter with another man says one of the men had his shirt off but nothing more graphic than kissing was shown.
Rutgers student Cassandra Cicco testified Friday in the trial.
The case sparked a national conversation about bullying of young gays after Ravi's roommate, Tyler Clementi, committed suicide days after the webcast in September 2010.
Cicco says Ravi told her he wanted to use his webcam to see if his roommate was gay. But she said he didn't seem to have a problem with homosexuality.
To convict Ravi of bias intimidation, prosecutors would need to show he acted because he was anti-gay.
Ravi, now 19, insists he committed no crime. In fact, he turned down a plea deal which included no jail time.
In the months before Clementi's suicide, a number of young gays who had allegedly experienced bullying had also killed themselves.
But it was the Rutgers case that sparked the "It Gets Better" campaign to offer support to young homosexuals.
