EMERYVILLE -- A woman found dead Thursday morning on the beach at Shorebird Park was a Fremont resident who committed suicide, authorities said Friday.

The 44-year-old woman's name was not released.

Fremont police said the woman's sister came to police headquarters about 1:15 p.m. Thursday to report her missing and told officers her sister had some mental health issues and was unstable. The woman told police her sister had threatened to drown herself in the Emeryville area.

The woman was last seen by a friend in San Jose about noon Wednesday, Fremont police said. She was supposed to be going to a doctor's appointment but never arrived.

The woman had already been found by a passer-by about 7:14 a.m. Thursday, wet and clothed on the park's beach, near Interstate 80 off Powell Street next to Chevy's Restaurant.

It was not known how long she had been on the beach before being found.

Police said the car she used to drive to Emeryville was found parked nearby.

Staff writer Erin Ivie contributed to this report