A man has been arrested on suspicion of decapitating his grandmother and escaping the scene with her head.
Luis Gustavo Aroyo-Lopez, 23, was arrested in San Francisco on Saturday - two days after Elvia Lopez-Arroyo was found dead.
The 64-year-old was discovered at a property in Santa Rosa, just north of the city, after police responded to a call of a possible homicide.
Investigators believe it was a "targeted attack" and said multiple weapons were found at the scene - although the weapon used to kill the woman is still to be ascertained.
Aroyo-Lopez was caught at the Transbay Transit Center on Mission Street after a police officer on foot recognised him from a state-wide law enforcement alert.
His grandmother's head was found on the south bank of the Santa Rosa Creek at about 7.30pm on the same day he was arrested.
Authorities said Aroyo-Lopez had recently been released from state prison, where he was serving time for assault with a deadly weapon, and was under community supervision.