OAKLAND — A woman who was videotaping as a BART officer killed an unarmed man testified Monday that the officer had not been acting overly aggressive toward the victim leading up to the shooting and that he appeared "dumbfounded" afterward.

Karina Vargas, who was one of several people at the scene who digitally recorded the New Year's Day incident, told the judge at the preliminary hearing for Johannes Mehserle that she believed other officers were behaving more aggressively at the time. And, she said, Oscar Grant didn't appear to be resisting arrest.

Videos taken of the incident show Mehserle -- who grew up in Napa -- firing a shot into Grant's back as the man lay face down on a train platform. The officers had detained Grant and four others at Oakland's Fruitvale station for allegedly fighting on a train.

"He wasn't that aggressive at all," Vargas said of Mehserle's behavior leading up to the shooting, on cross-examination by the defense. "He was handling him a little rough ... but he looked like he was doing what he had to do."

Mehserle, who has since resigned from the Bay Area Rapid Transit police department, has pleaded not guilty to a murder charge.

Attorney Michael Rains — who has said his client meant to use his stun gun but accidentally pulled his pistol instead — then asked Vargas how Mehserle looked after the shooting. She said he looked "dumbfounded."

"And shocked?" Rains said.

"Yes," Vargas replied.

Vargas and another witness, Margarita Carazo, testified Monday in Alameda County Superior Court that they started recording because they felt something bad was happening as the five men were detained at the station.

Their testimony and dramatic videos of the chaotic scene highlighted the first day of a preliminary hearing expected to last about two weeks.

The shooting — which grabbed national attention after videos of the incident began circulating on the Internet and television — continues to fuel community outrage and has led to numerous protests and arrests. On Monday, more than 150 people staged a relatively peaceful demonstration in support of Grant outside the courthouse.

Inside, prosecutors played Vargas and Carazo's videos. While Vargas' video panned away from Grant at the moment of the shooting, audio of the gunshot still provoked gasps in the courtroom. Grant's mother, Wanda Johnson, could be seen tearfully embracing her daughter.

Vargas and Carazo both said Grant appeared to be complying with police orders right up until the moment he was shot. They testified that several officers, led BART officer Anthony Pirone, were acting unnecessarily aggressive — and, Vargas said, more aggressive than Mehserle. Pirone has since been placed on paid leave.

"Oscar wasn't doing anything wrong, he wasn't fighting back or anything," Carazo said. "He didn't do anything wrong. He was just standing there."

Both witnesses said they didn't know Grant was killed until days later and decided to turn over their videos to the Grant family's lawyer.

Grant's uncle, Cephus "Bobby" Johnson, said after the hearing that seeing the videos in court was especially painful for the family.

"When you see a loved one that has been murdered, it's really striking to the soul," he said. "But we know it's something that we have to go through at this time to get justice for Oscar."