A South Bay woman last week admitted to police that she beat an elderly Cupertino woman to death with a hammer, according to authorities.
Suzanne Hernandez, 39, on Wednesday was arraigned in a Palo Alto courthouse, but did not enter a plea.
Police said on Friday that the suspect was found while running naked down a busy street in Cupertino. She was initially sent to the Santa Clara Valley Medical Center for a psychiatric evaluation.
It was only later that investigators linked Hernandez to what police say was a random and exceptionally brutal attack on a 74-year-old woman, Mary Willson
"It looks like the suspect entered through the back door while the victim was awake. It doesn't look like they knew each other in any way," said Stacey Capps with the Santa Clara County District Attorney's Office.
Hernandez confessed to the attack, which occurred in the living room of the victim's house.
Prosecutors believe the suspect could be suffering from mental health issues and expect her to plead guilty by reason of insanity.