BART officials are investigating whether the officer involved in a confrontation with an unruly rider Saturday violated new use-of-force policies the transit agency enacted after the well-publicized New Year's Day shooting of an unarmed passenger.

"The officer used the available information he had and acted on it. The question is, did he act within BART's use-of-force policy," BART spokesman Linton Johnson said Monday following a news conference at the agency's Oakland headquarters.

Meanwhile, Oakland civil rights attorney John Burris said he will represent the passenger in the criminal case against him and, if it becomes necessary, a civil case as well.

Both the officer and the passenger, 37-year-old Michael Joseph Gibson of San Leandro, were bloodied and injured in the melee at the West Oakland station.

Gibson's aunt, Sylvia Hawkins, said her nephew is bipolar, which can be characterized by manic mood swings. Daly City police said Gibson had been arrested and released hours before the BART scuffle on suspicion of assaulting a man aboard a SamTrans bus.

BART has not identified the officer, except to say he has been with BART police since May and was previously a Contra Costa sheriff's deputy. The officer, who required stitches for cuts on his face and suffered a concussion after a glass window shattered on him and Gibson, has been placed on paid leave because of his injuries.

The officer had gone to the train stopped at the West Oakland station about 5:40 p.m. Saturday after calls from passengers. Video taken by passengers shows Gibson inside the BART car, yelling at other riders.

The video, which was posted on YouTube, shows the officer telling Gibson to get off the train, then grabbing him and pulling him off the train and across the platform to a windowed wall. As they move close to the wall, the window shatters.

BART police already are under fire for their handling of another incident involving a reportedly unruly passenger. Former BART officer Johannes Mehserle has been charged with murder for shooting Oscar Grant III, 22, of Hayward, at the Fruitvale station following a Jan. 1 scuffle on a train.

In the wake of the shooting, BART changed its policies to mandate that any use of force be reported to a supervisor and investigated. Previously, only significant use of force was required to be reported.

To determine if policies were violated, BART officials are interviewing 12 witnesses to Saturday's confrontation and watching videos of the event, Daniel Hartwig, BART's patrol bureau commander, said Monday.

Burris -- the Oakland attorney who is also representing Grant's family in a civil suit against BART -- said he met with Gibson on Monday at Santa Rita Jail, where Gibson is being held on suspicion of battery and resisting an officer. Hartwig said formal charges are expected to be filed today by the Alameda County District Attorney's office.

"He has bandages around his forearm, but not on his head," Burris said. "It looks to me like his forearm hit the window or the window shattered on his forearm.

"I don't believe the officer intentionally tried to put his head through the window," Burris added. "I don't think he intended to do that. It was the degree of force he was using in manhandling Mr. Gibson."

Burris said he was "offended" that Gibson was booked on suspicion of resisting an officer "when the officer was the aggressive person."

Several experts who watched the video differed on whether the officer followed proper police procedure.

"It looks like the officer was being precipitous and jumping into the situation," said George Kirkham, a Florida criminologist and consultant who stressed his only knowledge of the confrontation is from the video. "The basic principles for dealing with mentally disturbed people are, 'Don't raise your voice, talk to them in a calm, even way, don't threaten them, get some backup.' "

All BART officers have received training in issues including dealing with mentally unbalanced suspects, as is mandated by the California Commission on Peace Officer Standards and Training, Johnson said.

"Prior to Jan. 1, we either met or exceeded the training," which requires a minimum of 24 hours every two years of continuing education, Johnson said. "We have increased it to 40 hours of training per year for officers" since the Grant shooting. That shooting also was recorded on passengers' cell phones and video cameras and posted on the Internet and shown on local television stations.

The officer involved in Saturday's incident has received more than the minimum required by POST, Hartwig said Monday.

Others offered differing views of the officers' actions.

"Assuming in general that an officer gets a call that someone is threatening people, he or she has to intervene," said Kim Colwell, head of litigation for Meyers Nave, one of two law firms BART hired to investigate the Jan. 1 shooting. "Sometimes it must be done quickly."

Another expert said the BART officer did as good a job as possible Saturday, judging by the video.

"The idea is to remove him from the situation," said Gregory Lee, a retired supervisory special agent with the Drug Enforcement Administration who has testified in federal use-of-force cases. "The guy was already flailing his arms. Get him off the train and onto the platform."

Earlier Saturday, Daly City police said Gibson had been arrested on suspicion of assaulting a man aboard a SamTrans bus parked at the Serramonte shopping center. Officers arrived about 11 a.m. and witnesses told them Gibson had kicked an 82-year-old man in the buttocks, said Sgt. David Mackriss. Gibson was arrested on suspicion of assault. He was booked on the Daly City Police Department, given a misdemeanor citation and released pending a January court appearance.

Gibson could face additional charges of elder abuse because of the age of the victim, Mackriss said.

Gibson is no stranger to run-ins with the law. Court records show he was convicted of domestic violence in Hayward in 2007 for punching the woman he lived with, who was pregnant with his child. Records show he was arrested twice this year in Hayward on suspicion of being drunk in public, once on suspicion of petty theft in Hayward in 2008, and twice in Hayward in 2007 on suspicion of being under the influence of methamphetamine. Charges in many of those cases were dismissed.

In October 2008, Gibson refused to participate in field sobriety tests, cursing police who responded to a report of a disturbance, according to the police report. In December 2008, when officers responded to a complaint of loud music from his apartment, Gibson advanced on an officer with clenched fists and was shot by a stun gun and arrested, police said. The outcome of those cases is unclear.

Staff writers Eric Kurhi, Robert Salonga and Sean Maher contributed to this report.