Muni slaying suspect had cache of guns, police say

Before killing 20-year-old Justin Valdez, Nikhom Thephakaysone had pulled one of his guns on two people in separate incidents in San Francisco's Ingleside neighborhood Before killing 20-year-old Justin Valdez, Nikhom Thephakaysone had pulled one of his guns on two people in separate incidents in San Francisco's Ingleside neighborhood Photo: Handout, San Francisco Police Photo: Handout, San Francisco Police Image 1 of / 4 Caption Close Muni slaying suspect had cache of guns, police say 1 / 4 Back to Gallery

The 30-year-old man accused of shooting a San Francisco State student to death Monday had amassed a cache of weapons and survival gear, and it was only a matter of time before he became violent, police said Thursday.

Before killing 20-year-old Justin Valdez, Nikhom Thephakaysone had pulled one of his guns on two people in separate incidents in San Francisco's Ingleside neighborhood, Police Chief Greg Suhr said at a news conference.

Then, shortly before 10 p.m. Monday, Thephakaysone boarded a Muni light-rail car near San Francisco State University. Valdez also boarded the railcar, and the suspect trailed him before shooting him in the back of the head as he exited in front of his home in the Ingleside at Randolph and Bright streets, Suhr said.

Even though the two lived in the same neighborhood, they did not know each other, and they had no other interaction on the ride, according to the chief.

Police arrested Thephakaysone the next day at his home three blocks away. There, officers seized two assault rifles, combat knives, razors, a first aid kit and other survival gear.

The district attorney's office said Thephakaysone will be charged with murder. His arraignment is scheduled for Friday.

Suhr said he did not know what motivated the suspect to shoot Valdez, nor why he had several weapons in his home.

"You'd be hard-pressed to understand why someone would possess this type of firepower," Suhr said.

Thephakaysone was in possession of $20,000 in cash upon his arrest, Suhr added.

The 30-year-old suspect was also a student at San Francisco State and lived on Lobos Street with his mother and stepfather, police said.

His parents told The Chronicle on Wednesday that they did not know about the reported weaponry in their home. They declined further comment.

A neighbor said the family was quiet and rarely interacted with those living nearby.

Valdez, a sophomore at San Francisco State, was from Garden Grove (Orange County) and had moved to San Francisco last year for school. Friends and family described him as extraordinarily outgoing and passionate about environmental causes.

He was studying to be an environmental engineer, his sister said.