SFPD announced the 30-year-old male suspect detained for charges of murder of SF State student Justin Valdez is also an SF State student, in a press conference today.

Valdez, a 20-year-old SF State sophomore, was shot in the back of the head and killed as he got off the M-Oceanview train at Randolph and Bright Streets in Ingleside at about 9:50 p.m. Monday night. SFPD arrested Nikhom Thephakaysone outside his Oceanview home the following day.

At the press conference, police revealed Thephakaysone pulled his .45 caliber handgun on two other people that night before shooting Valdez, and SFPD found $20,000 on Thephakaysone, according to KTVU.

Through a warranted search, SFPD found four knives and assault weapons in Thephakaysone’s home.

But police announced they still don’t know whether the shooting of Valdez is gang related or not. SFPD closed it’s investigation and gave responsibility for finding the motive to the district attorney, SFPD said.

Thephakaysone transferred to SF State in Fall 2008 as a full-time student. After a year he was a on-and-off student taking Open University classes. Open University classes are open to students not enrolled in a degree program regardless of prerequisites if there is space available.

Additional reporting from Brian Donovan