SAN FRANCISCO (KCBS) — Police said they discovered a large weapons cache at the home of a man accused of fatally shooting a San Francisco State University student earlier this week.

At a news conference at the Hall of Justice Thursday, police revealed 30-year-old Nikhom Thephakayson, identified as the suspect in the killing of a 20-year-old Justin Valdez, had assault rifles and other weapons discovered during a search of his home.

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The suspect has been booked with suspicion of murder in connection with the fatal shooting of Valdez on Monday night, after the two exited a Muni light-rail vehicle at Randolph and Bright streets.

Police Chief Greg Suhr said both were students at San Francisco State University, but did not appear to have any past connection.

Valdez was shot in the back as he was getting off a San Francisco Municipal Railway M-Ocean View light-rail vehicle, police Chief Greg Suhr said.

“He shot him in the back, unprovoked and for no apparent reason that we can find out at this point in time,” Suhr said.

Suhr said Thephakaysone brandished a 45-caliber handgun to two other people before the fatal shooting. He was arrested on Tuesday outside his home in the city’s Oceanview neighborhood.

Detectives found $20,000 in cash when they searched Thephakaysone’s home, but they found much more.

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“Two assault weapons, an M&M [semi-auto rifle], M10 7.62 caliber, and a Ruger Mini 14-223 firearm caliber, backpack and laptop computer, combat-type knives,” listed Suhr.

Suhr said the suspect lived at the home with his mother, stepfather and sister.

“You’d be hard-pressed to understand why somebody would possess this sort of firepower,” he said. “We’re just glad nothing played out other than it did” with the death of Valdez.

Valdez was a sophomore at San Francisco State and had started attending classes there last year. His sister attended Thursday’s news conference but did not speak to reporters.

Suhr said the victim’s family is asking for the public’s help in raising money to transport him back to Southern California to be buried. Valdez grew up in Garden Grove in Orange County.

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SFSU spokeswoman Ellen Griffin said Thephakaysone was admitted to as a transfer student in 2008 as a dietetics major and was a full-time student for a year, but has since been taking classes off-and-on, including this semester.

District Attorney’s office spokesman Alex Bastian said Thephakaysone is being charged with murder and is scheduled to be arraigned on Friday in San Francisco Superior Court.

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