O’Brien, of Methuen, a former National Guardsman, has filed a federal lawsuit against Williams, Nguyen, and the Boston Police Department. He alleges that he suffers from debilitating headaches and dizziness as a result of the arrest, and that his career as a correction officer and his aspirations to join the Army’s Special Forces have been “flipped upside down.’’

“It was like a kick in the gut,’’ he said. “I was expecting to be exonerated. I was expecting them to come out to say: ‘This is a lie. These charges aren’t true. This arrest was false.’ As happy as I am they’re charging him with something, it’s tough. It’s a knock at your credibility as a person.’’

Despite the findings against Williams, O’Brien said it was “a sickening feeling’’ to read the Internal Affairs Division report clearing officers of other charges.

Williams’s partner, Officer Diep Hung Nguyen, was cleared of three charges, including using unnecessary force, as were the four other officers involved in the arrest. Williams was cleared on four charges, including two counts of violating the rule for respectful treatment.

Michael P. O’Brien, a 30-year-old Middlesex County corrections officer, filed a civilian complaint against Williams and five other officers who arrested him on Hanover Street on March 16, 2009. O’Brien said that Williams drove his head into the sidewalk and choked him after he began recording Williams and his partner with a cellphone as the two officers responded to a minor traffic accident.

“He’s absolutely testified honestly and truthfully about the incident that occurred,’’ Louison said. “Any conflicts about the incident were the result of a fast and rapidly evolving incident.’’

Williams was fired from the force in 1999 after being implicated in the racially charged 1995 beating of undercover police officer Michael Cox, then reinstated with nearly $550,000 in back pay after a civil service arbitration in 2005.

As a result, Officer David C. Williams has been placed on paid administrative leave, the Boston Police Department said, and could lose his job under Police Commissioner Edward F. Davis’s nearly 19-month-old policy of dismissing officers who lie in the line of duty, to internal affairs investigators, or in court . Williams is appealing the finding, and a hearing is scheduled for later this month.

A Boston police officer at the center of one of the most notorious police brutality cases in city history used unreasonable force while arresting a man in the North End in 2009, then lied about the episode to department investigators, according to an Internal Affairs Division report obtained by the Globe.

Davis was not available to be interviewed about the Internal Affairs Division report. Asked if Williams should be fired, Police Department spokeswoman Elaine Driscoll said it was inappropriate to discuss the officer’s possible discipline.

“Discipline could result in a number of things, including termination,’’ Driscoll said. “The investigation was fair and methodical. Every officer is entitled to due process.’’

Asked if this is a test of Davis’s highly touted antilying policy, Driscoll would only say: “The charges sustained are very serious, and the police commissioner will treat them as such.’’

O’Brien was arrested after Williams and Nguyen responded to a fender-bender on Hanover St. According to police and court documents, O’Brien and two friends were in a car that backed down Hanover Street and clipped a double-parked vehicle. In his incident report, Williams wrote that O’Brien “became very unruly’’ and “pushed Officer Nguyen.’’

But according to the Internal Affairs report obtained by the Globe, Williams, who is 6-foot-3 and 242 pounds, used an “unreasonable amount of force’’ to arrest O’Brien, who was 5-foot-9 and 160 pounds at the time. The report also found that Williams, 48, was “untruthful in his statements’’ when interviewed by department investigators.

The Internal Affairs Division ruled that Nguyen, 33, used “reasonable and proper force’’ to arrest O’Brien and that Nguyen properly arrested O’Brien for disorderly conduct. The report also found that while Nguyen directed profanity at O’Brien and an unnamed witness to the arrest, investigators were “unable to prove or disprove’’ a violation of department rules mandating respectful treatment of civilians.

O’Brien said he did not see the other four officers who took part in the arrest and does not know how they became part of the investigation.

The notice of findings, signed by Superintendent Kenneth Fong of the Police Department’s Bureau of Professional Standards, provides no details about how investigators came to their conclusions, nor does it shed light on how Williams was untruthful during the internal investigation.

O’Brien and his attorney, Howard Friedman, said he could not discuss the case or his lawsuit because the information is being kept secret at the urging of the police under a court order.

But O’Brien was willing to say what punishment he believes Williams deserves. “He should be fired; he should have been fired a long time ago,’’ O’Brien said. “I was astonished that someone with such a history could be working on the Police Department.’’