The father of William David Raff, the man fatally shot by Palo Alto police on Christmas night, said his only child had a long history of mental illness. But he called his son's death "an unjust shooting."

Raff, 31, allegedly called police to the La Selva Group mental health residential center on the 600 block of Forest Avenue in Palo Alto claiming that someone wanted to harm a person at the home. When police arrived, Raff, who lived there, was standing in the street. He allegedly lunged at police while holding a knife, according to police.

But his father, Garold Raff, said he and his former wife believe their son is the victim of police using excessive force.

He admitted that he did not know all of the circumstances surrounding the incident, but if his son had been armed with a gun, Garold Raff said he could understand the necessity for officers to shoot.

"Reportedly, my son had a butter knife, not a lethal weapon, and for them to just shoot him ... this is so far off any reason," he said, referring to news reports that quoted a resident of the house.

"It's just awful. It was challenging enough to just help him, and to have him treated this way was so excessive. ... In our opinion, it was mishandled," he said from his home in Southern California on Monday evening.

He and Raff's mother are exploring potential litigation, he said.

Palo Alto police spokesman Zach Perron said he could not comment on whether William Raff had been holding a butter knife, since the incident is still under investigation. But in an update to this story, on Tuesday he said the metal knife was 9 inches long, had a slightly serrated edge and a tapered, slightly-rounded tip. He described it as a table knife as opposed to the smaller, formal 3-inch butter knife.

Garold Raff also lamented the mental health system that should have helped protect their son, who had schizoaffective disorder. The system leaves parents out of the loop and their severely mentally ill adult children vulnerable, he said.

"We are in so much grief," Garold Raff said. His son had only resided at the La Selva house about a week.

When William Raff was a child, there was no indication of the illness that was to follow. He was a "perfect" son growing up, his father said. He never went through the terrible twos nor was he a troubled teenager. He learned to ski and surf, and he played tournament golf at the country club with his grandmother.

But his parents became puzzled when it took eight years for their son to graduate from college. He studied business at San Diego State University and then landscape architecture at Cal Poly Pomona, where he earned a degree. They didn't know until he left college — and no longer had access to his medications — that their son had a devastating mental illness.

What followed were numerous hospitalizations in psychiatric wards, stabilization with medication, then spirals downward when he stopped taking the medication. There were periods of paranoia and illusions of grandiosity.

People with schizoaffective disorder, a serious mental disorder that can involve psychotic breaks from reality and wide mood swings, often must take a cocktail of medications that produce many side effects. Patients sometimes have trouble accepting a lifetime of heavy medication, and Raff would go through cycles — getting stable, seeming to stay on his medicines, then falling away and returning to illness and psychiatric facilities, his father said.

Several months ago, Garold Raff purchased a home in Felton where his son was living. Raff liked the Bay Area — he disliked Southern California — and he held many jobs while living here. Early on, he worked for a landscaping company as an installer, his father said, laboring 10 hours a day four days a week. But then the company upped his 10-hour days to five.

"He burned out," his father said.

As time went on, his illness became more severe, his father said. About a month ago, Raff attempted suicide, was taken to a hospital emergency room and later placed in a locked psychiatric ward. It was his second attempt in a year. The first had taken place in Southern California, according to his father.

After becoming stable, he was transferred to La Selva. He was allowed to sign out to take a walk on the street for a short period of time.

But the overall restrictions on his life because of his illness were sometimes frustrating, his father said.

"Every now and then he was disgusted and excitable about the circumstances he was living in," his father said.

Since his son entered La Selva, Garold Raff said he only had a few passing conversations with staff. But he had a feeling that his son's mental state was unraveling again.

"I didn't sense that things were going right; I wanted to talk to them. I was trying to find out what they do. I was getting nervous," Garold Raff said. "It was the same feeling of 'I don't know where this is going' sort of thing. The system just leaks away."

As an adult, Raff was protected by privacy laws that often left his parents outside of the circle of his care, his father said. There were "huge gaps" in his son's treatment, and overall, Garold Raff found the profession of psychiatric care to be "erratic as hell."

"I know it's not an exacting profession; it's sort of a fishing expedition," he said.

"I never felt that the system allowed me to receive adequate information to feel comfortable with his conditions," he said.

When asked Monday if anyone at La Selva had reached out to him since his son's death, Garold Raff was silent for a long time — so long that it seemed as though the phone line had disconnected.

"I'm stunned," he said, pausing again. "No, I haven't heard from them."

Michael Hayes — director of development and communications for the Momentum For Mental Health, the nonprofit parent organization to La Selva Group — said in an email on Monday that the organization could not comment to the public on details related to the incident.

"As you can imagine there is much sensitivity around this topic and really no ability to elaborate given this is still an open investigation," he wrote.

Momentum released a statement Monday morning that read in part: "Our residential program ... is a Transitional Residential program. It is fully licensed by the State of California Department of Social Services and Department of Health since 1979.

"This program is staffed by over a dozen mental health professionals — including psychiatrists, psychologists, nursing staff and experienced clinicians — who usually work with 12 residents at a time."

Garold Raff said he holds a picture in his mind of his son before the illness robbed him of his life.

"He was really a handsome kid — blue eyes, blonde hair and a great smile," he said.