The closest thing to emotion any member of the Ravi family showed yesterday came in the worried glances, exchanged shortly after the lunch hour yesterday at Middlesex (N.J.) County Courthouse.

Dharun Ravi sat composed at the defense table in his black suit with a blue shirt and pink tie, charged with invasion of privacy, bias intimidation, witness tampering and hindering arrest in connection to the September 2010 suicide of Rutgers U. student Tyler Clementi.

But his parents exchanged looks of surprise when the prosecutors called Molly Wei, a former Rutgers student considered Ravi’s accomplice, to the witness stand.

No one anticipated the key witness for the prosecution to testify on Day 2 of the trial, which is expected to last three to four weeks.

But after early morning testimony from Rutgers sophomore Pooja Kolluri, Rutgers Associate Director for Residence Life William O’Brien and the cross-examination of Rutgers School of Engineering sophomore Scott Xu, Wei took the stand.

The prosecutors took the opportunity to explain how the video of Clementi with an older man appeared on her computer and how Ravi reacted afterward.

“He thought we were going to get in trouble, so he wanted to make it seem like it was more of an accident,” said Wei, who transferred from RU. “We knew that there would be a video.”

The defense used the cross-examination to prove Ravi had no homophobic motivation.

“I didn’t get the sense that he didn’t like Tyler,” Wei said, “just that they were different.”

That point will prove vital in the case, as Ravi could face a 10-year prison sentence should the 15-member jury find him guilty of the top bias intimidation charge for acting with malice against Clementi because of his sexual orientation.

Wei, who the Rutgers University Police Department initially arrested along with Ravi, signed a waiver of indictment for two counts invasion of privacy — fourth degree for viewing without consent and third degree for broadcasting without consent.

She is part of a pre-trial intervention program that will dismiss the charges upon completion of 300 hours of community service, payment of a fee, counseling about cyberbullying and alternate lifestyles, and truthful testimony in court.

That testimony began with a detailed account of her relationship with Ravi.

The pair first met in middle school, but fell out of touch when they attended West Windsor-Plainsboro North High School, which Kolluri and Xu also attended.

When Wei arrived at her Davidson Hall room in August 2010, she realized Ravi lived across the hall, and the pair became friendly again, she said.

Ravi told her he thought his roommate Clementi might be gay, but it was a “brief, casual mention,” Wei said, and it did not come up again.

Xu expressed the same sentiment in his cross-examination from defense attorney Steve Altman. Xu was closer friends with Ravi in high school — they played Ultimate Frisbee together and discussed their roommate assignments when notified.

Xu heard Clementi might be gay, but learned of Clementi’s encounter via Ravi’s Twitter account.

“It was a memorable tweet,” Xu said. “It stood out. It’s not something you see every day.”

Wei said Ravi tweeted from her computer after watching the video, enabled by an “auto-accept” feature on Ravi’s desktop computer that activated his video chat when it received a request.

They witnessed Clementi kissing an older man, but closed it after about two seconds, she said.

“Initially we were saying we couldn’t tell anyone what happened because of how shocking it was,” Wei said. “It shouldn’t have happened, and we saw something we weren’t expecting to see. It just felt weird.”

But Wei said she accessed the video chat again later that night — with four girl friends in the room, not Ravi.

“It was the exact same image, except they had taken their tops off,” Wei said.

Kolluri was among those who saw the video the second time, but she said she had no idea what she would see when she was told to gather around Wei’s computer.

Ravi entered the room afterward and offered little reaction when told what they saw on the video chat. He thought Clementi might be gay and wanted to confirm it, Kolluri said, but Ravi also wanted to make sure things in his room were not touched.

Altman again argued that point in the cross-examination with Wei.

There were no discussions about making Clementi fearful she said.

Once the RUPD became involved, it was Ravi and Wei who were afraid.

Wei said she saw an officer knock on Ravi’s door on Sept. 23, 2010, but there was no answer and the officer left. Ravi told Wei that he was in his room, she said.

Wei went to police headquarters that day, when an officer picked her up from class in an unmarked vehicle. She exchanged text messages with Ravi from the station.

“Did you tell them we did it on purpose?” Ravi had asked. “What did you tell them when they asked why we turned it on?”

Ravi also asked her if the police mentioned another video from Sept. 21, 2010, when he tweeted a second time after Clementi again asked to have the room to himself.

While testifying, Wei said she was unaware of another video from that night, but believed rumors already began to circulate about Clementi’s relationship with another man, and that Clementi caught on.

Clementi requested a room change at 3:55 a.m. that day, according to O’Brien’s testimony. Clementi’s request read “roommate used webcam to spy on me/want a single room,” but Judge Glenn Berman only allowed the second part into court.

The first part of the statement was not shown to the jury after Berman determined it was “hearsay” evidence and inadmissible in court. When Ravi and Wei first viewed the video stream, they had no idea Clementi was aware, Wei said.

Berman halted the cross-examination at 4 p.m., and it will resume again today.