Staff noticed he was missing during early morning rounds. They believe he escaped though an elevator shaft. The San Mateo County Sheriff's Office is concerned, because Derrick Sanders, 34, is a high risk sex offender.
"He's a parolee; he has violence in his history, he has prior sex offense in his history," Lt. Larry Schumaker said. "That fact that he also has a sex offense with minors is definitely high risk in our community."
Sanders was placed at Cordilleras by parole officers. It's a locked facility, but it's a treatment center. The company that provides the care describes it as a rehabilitation center.
"Growing up here I never heard of anyone escaping or anything or seeing anything weird, but knowing about this is kind of scary," Jagruti Patel said.
Patel likes to bring her one and 2-year-old daughters to her childhood home so they can see their grandparents. The house is just down the street from Cordilleras.
"I'm afraid for my children now," she said. "I don't even know how often I want to come back here to my parents house because they're so close."
Patel doesn't normally go by the facility, but other neighbors do because it's right next to the Pulgas Ridge Open Space Preserve.
"Once in a while you see one of the patients walking around," neighbor Nicholas Tachavirat said. "I think they let him out for that purpose, I don't know."
Most trail-goers say they aren't too concerned about the escape.
"There are mountain lions up there every so often so that's what I'm more conscious about than any wild or loose parolees or something here," San Carlos resident Grant Kolling said.
But authorities want sanders back in custody as soon as possible, so area agencies have been notified.
"He's basically a transient; he has some family here in the county and also in Oakland so we believe that he's probably walking away from this area," Schumaker said.
Sanders is 5 foot 11 inches tall, weighs 165 pounds and was last seen wearing a red shirt and blue jeans. Police stress that he should not be approached.