A federal court jury has cleared two San Francisco police officers of wrongdoing for fatally shooting a mentally ill man in his home in December 2010.

After hearing conflicting accounts of the officers’ confrontation with Vinh “Tony” Bui at a trial last week, U.S. District Court jurors rejected family members’ claims that the officers used excessive force or acted negligently when they shot him.

Police said they went to the home on Bacon Street in the Portola neighborhood in response to a report that Bui had stabbed a 15-year-old girl. Family members said afterward that Bui, 46, diagnosed with schizophrenia 15 years earlier, had suffered a psychotic episode at the sound of a slamming door and cut one of his niece’s friends in the back with an X-Acto knife, which he had previously used as a letter opener.

The officers, Austin Wilson and Tony Ortiz, said the people they found in the home, who were mostly teenage friends and cousins of Bui’s niece, seemed reluctant to say who was hurt and did not appear in distress. Ortiz messaged a dispatcher to say there was no emergency, but then the girl showed them a puncture wound on her lower back.

The officers asked where the man with the knife was, and the teens said he was in a bathroom down the hall. At that point, said Cindy Tran, one of Bui’s sisters, she repeatedly tried to tell the officers about Bui’s schizophrenia, but the officers said later they did not remember hearing anything about that.

Witnesses disagreed about what happened next. The teenagers testifying in support of the lawsuit said Bui shuffled out of the bathroom slowly with the knife at his side, bent at the waist and turning away from the officers. But Wilson and Ortiz said Bui walked toward them waving the knife.

After he ignored repeated commands to drop the weapon, they said, they fired three shots at him from a few feet away.

Another sister, Rose Bui, said her brother, at 5 feet 6 and 135 pounds, posed no threat to the officers and that they made no attempt to disarm him or use pepper spray.

San Francisco’s Office of Citizen Complaints issued a report before the trial saying that the officers’ use of lethal force had been reasonable but that their “investigative and tactical errors jeopardized their own safety and those within the residence and also compromised the officers’ ability to consider alternatives to deadly force.” The jury did not learn of the report, which was excluded from evidence at the request of the city’s lawyers.

Deputy City Attorney Sean Connolly, who represented the city in the case, said he was grateful for the jury verdict but “there are no winners or losers in cases like these. Any loss of life is tragic. Police officers have a difficult and unenviable job and are frequently called upon to make life-and-death decisions in dangerous and evolving circumstances.”

Lawyers for Bui’s family could not be reached for comment.

Bob Egelko is a San Francisco Chronicle staff writer. Email: begelko@sfchronicle.com Twitter:@BobEgelko