A 45-year-old San Francisco man suffering from what investigators call "psychiatric issues" is charged with murder in a bizarre attack in a San Franciso parking garage.
The San Francisco Chronicle reports the attack nearly decapitated Yoshioka, who died at the scene.
The attack happened in the parking garage above the OfficeMax at 3700 Geary Blvd. at about 2:45 p.m.
People who witnessed the attack were able to detain Fong inside the garage until police arrived and arrested him.
"We're not entirely sure what provoked the incident," Assistant District Attorney George Butterworth said Friday.
Fong appears not to have known the victim and has no criminal history, he added.
Fong is due back in court Monday.