Thephakaysone appeared in court this afternoon where he was appointed a public defender. His arraignment was continued to Tuesday.
On Monday, Valdez boarded the M train at 19th and Holloway streets, right in front of SF State at about 9:40 p.m -- and Thephakaysone boarded the train right behind Valdez, according to the DA.
As the victim attempted to exit the train at the intersection of Randolph and Bright streets, Thephakaysone allegedly pulled out a .45-caliber pistol, pointed it at the back of Valdez and fired a single, fatal shot. The bullet tore through the victim's back, piercing his left lung and left heart ventricle, lodging in the soft tissue of his skin.
Valdez can be heard on the video captured by Muni cameras crying for help before he died.
Thephakaysone got off the bus and walked home.
He was arrested the next day and booked on murder charges; police later found three weapons at the suspect's home, including a pistol and two semi-automatic rifles. One of the rifles had a pistol grip, which is an illegal modification of the stock, prosecutors said. They also discovered $20,000 in cash.
"This is a wanton killing. There was absolutely no reason for this killing other than pure violence," District Attorney George Gascón said outside the courthouse speaking to a throng of reporters. "This is a cold and calculated murder. This individual went out hunting that night and unfortunately Mr. Valdez was at the wrong place at the wrong time."
The DA's office is charging Thephakaysone with one count of murder with the aggravated circumstance of using a hand gun and assault for an earlier incident where the suspect reportedly pressed his gun against a person's back. The person felt the gun and jumped on Muni. Gascón said that the suspect didn't have the courage yet kill the first victim, who waited until he got home before calling the police.
Thephakaysone is also being charged with possession of an illegal assault rifle, which was found when police searched his home.
Gascón said the video evidence indicated that Thephakaysone was out to kill somebody -- the suspect had tapped his gun on the window of a Thai restaurant window earlier in the night, the DA said. The people inside immediately called 911.
All the incidents occurred in the SF State vicinity. Thephakaysone was also an SF State student, attending classes sporadically since 2008.