The mystery man whose sexual encounter with a Rutgers University student was spied on by an Indian-origin student through a webcam made his first public appearance in court on Friday and testified that he saw a camera lens pointed toward the bed where he and his friends lay in a 'compromising position'.

The man's identity has been fiercely protected by the court and has been known only as 'MB' in the ongoing trial against Dharun Ravi, who is accused of invasion of privacy and bias intimidation of his roommate Tyler Clementi.

Clementi committed suicide days after Ravi secretly saw him kissing MB through his webcam. "I had just glanced over my shoulder and I had noticed there was a webcam that was faced toward the direction of the bed, and I just thought it was kind of strange," MB said during his testimony at the Middlesex County Courthouse in New Jersey near here.

"Just being in a compromising position and seeing a camera lens — I guess it just stuck out to me that if you were sitting at a desk using the computer, that camera would not be facing that direction, it would be facing the person at the computer."

MB further said when he left Clementi's room on the night of September 19, he saw a group of students hanging around the hallway of the dormitory, apparently joking and looking at him in an "unsettling" way. He told the court:

"I saw like a group of people standing there and they were looking at me. It seemed like they were looking at me and it seemed kind of unsettling. Had they been in the street or somewhere other than this building I would have asked them why they were looking at me," he said.

"I felt a little uneasy about it," MB added. MB returned to the dorm two days later and the two men again had an intimate encounter. He said: "We were both laying together in his bed. I could hear people talking in the courtyard. People joking, people laughing. It seemed like the jokes were at somebody else's expense."

MB told the court he had met Clementi in an online chat room for gay men in early August 2010. The two had then exchanged text messages for several weeks. He went to Rutgers to meet Clementi for the first time on September 16, 2010. Ravi was in the room that time.

"I just didn't want his roommate to have trouble with two gay lovers in a room that he shared. I was just trying to be respectful of his roommate. Our intentions were to get intimate," he said.

The trial is being televised live but when MB, seen as a star witness in the case, came into the courtroom to testify, the judge told thsoe present that they could not record or photograph the man.

Only MB's hands were shown on the webcast as he gave his testimony in the court. His identity has been concealed because he is considered a victim of an alleged sex crime.

According to the New Jersey Star Ledger newspaper, MB appeared to be in his late 20s or early 30s, has close cropped black hair and wore a blue and white striped shirt. He appeared a little nervous as he entered the courtroom.

Ravi has not been charged in connection with Clementi's death, but faces upto 10 years in prison if convicted on hate rime charges.