LOS ANGELES-- A farewell note left behind by the Santa Monica gunman expressed remorse for the killing of his father and brother but provided no explanation for the rampage that left them and three others dead.
Police Chief Jacqueline Seabrooks said that the three- to four-page handwritten note was found on John Zawahri's body after he was shot and killed June 7 by officers on the campus of Santa Monica College.
The 23-year-old Zawahri also used the note to say goodbye to friends and expressed hope that his mother would be taken care of and receive recompense from his father's estate.
Investigators believe mental illness played a role in the killings, Seabrooks said at a news conference Thursday.
"We know his was a troubled life and that he experienced mental health challenges," Seabrooks said. "We believe that his mental health challenges likely played a role in his decisions to shoot and kill both his father and his brother, to set fire to the family home, and to go on a 13-minute shooting spree spanning roughly 1.5 miles and which left five innocent people dead and three people injured."
Zawahri apparently built his own .223-caliber assault rifle, using it to shoot his father and brother before he set fire to their family home, officials said earlier Thursday.
Zawahri's mother was out of the country visiting family in Lebanon during Friday's rampage but cut short her trip and returned home Sunday. She has been interviewed by detectives.
Zawahri's rampage ended when police killed him in the Santa Monica College library Friday. To get there, he had carjacked a woman, directing her to the college and having her stop so he could fire at vehicles and strangers. Police still did not know why he chose to go to the college, why he targeted those killed or why he chose that day.
Santa Monica police plan to work with the FBI to understand Zawahri's psychological makeup and motivation, Seabrooks said.