LOS ANGELES (AP) — A graduate student who was shot to death during a furious struggle with campus police at California State University, San Bernardino, had a long history of mental illness and had stopped taking his medication at least a week earlier but hadn't appeared to be violent, authorities said Monday.

Bartholomew Williams, 38, was shot five times on Saturday night while battling three officers who had tried to handcuff him and take him away for a mental evaluation after he appeared irrational, said Sgt. Gary Robertson of the city Police Department, which is handling the shooting investigation.

Williams mother told Robertson that her son had been diagnosed with bipolar disorder about 17 years ago, the sergeant said.

"She said she believed he'd been off his medication for a week at least and had not been taking it frequently for the last two to three months," he said.

Bipolar disorder — formerly called manic depression — can cause drastic mood swings if untreated. In severe cases, sufferers can alternate from frantically upbeat and energetic to lethargic and suicidal.

"My understanding is (Williams) had a campus doctor who was prescribing medication for him," Robertson said. "He could either be high or low or anywhere in between ... hyper-active or really depressed."

Robertson said he has heard no concerns about violence.

"We have not been able to see that he exhibited violent tendencies other than being loud and obnoxious ... he was more of a shouter," the sergeant said.

Williams was working toward a master's degree in educational-instructional technology since summer of 2011. He had taken only one course during the quarter that ended Friday, and it was unclear how close he was to earning his degree, campus spokesman Sid Robinson said.

Williams lived across the street from the campus in an apartment-style complex on school-owned property and shared his suite of rooms with three other men, Robinson said.

The school held its graduation ceremonies hours before the confrontation, and there were few students left on campus, Robinson said.

Campus police had contacted Williams twice earlier that day, said city police Lt. Paul Williams, who is no relation. Once was in a parking lot and an hour later, officers checked up on him at his rooms, he said.

He appeared to be acting erratically but not violently, and the situations appeared to have been resolved, Robertson said.

During a third call, however, officers knocked on Williams' door and asked him to come out into the hallway, where they determined he was making "nonsensical" statements, Robertson said.

His roommates were not home at the time.

The one female and two male officers ordered the 6-foot-2, 205-pound Williams to turn around so they could handcuff him and take him to a hospital for a mental evaluation but he resisted, Robertson said.

"It went to struggling, pepper spray, baton strikes," the sergeant said.

The officers did not have stun guns, authorities said.

Police said Williams fought with furious strength, and at one point the officers were concerned because he had one handcuff on a wrist but the other, made of heavy metal, was swinging around dangerously.

During the struggle that lasted at least eight minutes and perhaps as long as 15, Williams managed to grab an officers' pepper-spray and use it on an officer, grappled over another officer's baton, and stood over an officer and kicked him in the chest and head, Robertson said.

"Officers fearing for that officer's life believed they had no other means than the use of deadly force," Williams said.

All three officers were placed on paid administrative leave pending the outcome of the investigation. The woman officer was treated for a sprained thumb, Robertson said.