Baca, 82, suffers from Alzheimer's disease, his attorneys said in 2016.
He was last seen at his home Sunday at 4:38 p.m. and his family reported him missing at 7:30 p.m.
San Marino police searched for him, with support from the LASD and neighboring police agencies.
El Monte police were dispatched on a service call to a restaurant in their city at 12:34 a.m. They found Baca there. Firefighters examined him and found him in good condition, with an identification bracelet listing contact info. He was returned home and reunited with his family.
Baca served as elected sheriff from 1998 to 2014. In 2017, he was sentenced to three years in federal prison for obstructing an FBI investigation into abuse in county jails. He reported to prison in February 2020 and was released in January 2022.