The alleged shooter of SF State sophomore Justin Valdez faces three felony charges including murder, and is being held without bail, the San Francisco District Attorney’s office announced today in a press release.

Nikhom Thephakaysone, 30, is charged with murder, assault with a deadly weapon and possession of an illegal assault weapon.

“Due to witnesses and outstanding police work, this defendant is now off our streets and will be prosecuted to the fullest extent,” District Attorney George Gascón said in the release.

Police said Thephakaysone shot  20-year-old Valdez in the back of the head Monday night at about 9:50 p.m. as he got off an eastbound M-Oceanview Muni train at Randolph and Bright Streets in Ingleside.

Police arrested Thephakaysone in connection with the fatal shooting at his Oceanview home Tuesday where they discovered assault weapons, four knives and $20,000 cash.

Thephakaysone allegedly assaulted another man with a gun. Police said bystanders saw Thephakaysone brandish the weapon outside of a Thai restaurant before shooting Valdez Monday night.

Thephakaysone, also an SF State student, transferred in Fall 2008 as a full-time student. After a year he was a on-and-off student taking Open University classes.

The DA office scheduled Thephakaysone’s arraignment for Wednesday at 9 a.m., Director of Communications Stephanie Ong Stillman said.