Kirk Ryan Kimberly, an 18-year-old found dead in a shallow grave near Sonoma State University Wednesday night, suffered multiple stab wounds, the Sonoma County Sheriff's Office said.
Detectives, who continue to piece together evidence around the clock, said on Saturday that they do not believe that Sonoma State students had anything to do with the attack on the Cotati resident. Police added that the violent act was not random and was an "isolated incident."
Further specifics regarding the attack were not made available by authorities.
Kimberly had been missing since Oct. 17, when he was last seen leaving Cotati on his white bicycle to meet a friend in Rohnert Park, according to the Cotati Police Department.
He graduated from Rancho Cotate High School in Rohnert Park last year and had been working at a local pizza shop ever since.
Kimberly's friend Gema Ramirez described the teen as having "a really humble smile and bright eyes."
For the last three days, Ramirez said she kept hoping it wasn't her friend who had died.
But her worst fears were confirmed Thursday night.
"I hope that he wasn't in pain," Ramirez said.
Who would have killed Kimberly and why has not been revealed. However, the preliminary cause of death "is at the hands of another," the sheriff's office said, and investigators are treating it as a homicide.
"I think he was having some issues, some personal issues," said Sgt. Spencer Crum.
Anyone who has information about Kimberly’s disappearance or has knowledge of the incident is asked to call Detective Horsman of the Sheriff’s Violent Crimes Unit at 707-565-2185.