By Steve Gorman
LOS ANGELES (Reuters) - A three-page farewell note was found on the body of a California gunman who shot five people to death last week in Santa Monica, apologizing for killing his father and brother, who were among those slain, police said on Thursday.
Police also revealed that the assault-style rifle carried by John Zawahri, 23, whose rampage last Friday ended when he was shot to death by police in the library of Santa Monica College, had been assembled out of component parts he ordered from out of state.
Investigators are seeking to determine whether Zawahri, who had tried but failed to buy a weapon in 2011, assembled the gun himself or had someone else do it for him, Santa Monica police spokesman Sergeant Richard Lewis said.
The former part-time college student had also converted a vintage .44-caliber black-powder handgun into a .45-caliber revolver that he carried with him last week, Lewis said.
He added that Zawahri had tried to purchase a weapon in 2011 but was denied permission by the California Department of Justice in a form letter recovered by police after last week's shootings. Police have yet to determine why Zawahri was denied the purchase or what kind of gun he had tried to acquire.
The handwritten note found on Zawahri's body said he was sorry for killing his father and older brother, who were found shot to death in their home by firefighters called to put out a fire that engulfed part of the house.
The note also bid goodbye to friends and expressed hope that his mother, who was estranged from Zawahri's father and was out of the country at the time of the killings, would be provided for financially, Lewis said.
But the letter offered no explanation for why Zawahri killed his father and brother or went on the subsequent shooting spree through the seaside town west of Los Angeles that left three other people dead at Santa Monica College.
"It was a farewell letter, basically, apologizing for what he did to his brother and his dad, and hoping that his mother would be taken care of. That's it," Lewis said.
He made no mention in the letter of marital strife known to have existed between his parents or any other problems, nor did he express any anger, Lewis said.
Even though the semi-automatic rifle wielded by Zawahri was assembled from component parts, it was illegal under California's strict gun laws, Lewis said. California has banned the purchase and possession of assault-style weapons unless they were acquired by the owner before June 1989.
Santa Monica Police Chief Jacqueline Seabrooks, in a news conference called by police to disclose new details of the investigation, also said investigators believe mental illness was a factor in Zawahri's outburst of gun violence.
Police previously have cited an encounter they say Zawahri had with law enforcement as a juvenile in which he was taken into custody and placed under a 72-hour "psychiatric hold" in 2006, when he would have been 16 or 17 years old.
California law allows police to involuntarily confine a person for up to three days in the psychiatric unit of a hospital if that individual is deemed a danger to oneself or others or is "gravely disabled."
The incident seven years ago resulted in police being called to his family's home, but the circumstances surrounding the incident have not been disclosed by police.
(Reporting by Steve Gorman; Editing by Cynthia Johnston and Lisa Shumaker)