The man believed to be the Santa Monica rampage shooter left a note expressing sorrow for the death of his father and brother, police said tonight.

The also said farewell to some friends and stated that he wished that his mother was taken care of financially, according to Santa Monica police officials:

They also announced the AR 15-like, assault-type weapon he used in the rampage had been pieced together from “gun components from various sources throughout the country,” according to police Chief Jacqueline Seabrooks.

She also said he converted a vintage or antique handgun he carried during the attack to fire modern, .45-caliber bullets; cops found homemade zip guns in a burned out room in the home where the father and brother were killed police said.

In 2011 the state Department of Justice denied his attempt to purchase a gun, Seabrooks told reporters at a news conference tonight.

Detectives still aren't 100 percent clear on what sparked the rampage, though it has been widely reported that Zawahri had mental issues.

Credit: Zawahri in the SMC library, according to the SMPD.

Credit: Zawahri in the SMC library, according to the SMPD.

A search of Zawarhi's home in 2006 turned up “materials to make some type of explosives,” Santa Monica-Malibu Unified School District board member Oscar de la Torre told us.

Police had gone to the residence after school administrators expressed concern about the then-teenager. De la Torre says the district superintendent briefed him on the search afterward.

Cops sent Zawahri to a mental institution for a 72-hour hold and evaluation, according to reports. His parents underwent a bitter divorce when Zawahri was a child.

Police say shortly before noon one week ago today Zawahri killed his father and brother and set their home on fire before carjacking a woman and forcing her to drive to Santa Monica College.

He opened fire on cars and buses along the way, ultimately killing Marcela Dia Franco, her 68-year-old father, Carlos Franco, in their SUV, police said. Once on campus he fatally shot Margarita Gomez, also 68, as she collected recyclables.

He went inside the school library, apparently to continue shooting, but cops were hot on his tail and cut him down there.

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