On Tuesday afternoon, at approximately 2 p.m., a search of the Foothill Ranch Park was initiated by Orange County sheriff's investigators.
Bernstein, who was visiting relatives while on winter break from the University of Pennsylvania, went missing after going to Borrego Park with a friend to meet another person, said Annee Della Donna, an attorney and friend of the family.
Several search operations were conducted over the week for Bernstein after his parents reported him missing to the Orange County Sheriff department.
An autopsy was scheduled for Wednesday, and the case is now being investigated as a homicide, according to the sheriff's office.
Investigators say they are following multiple leads, but do not yet have a suspect in custody.
"As this investigation moves from search and rescue to homicide investigation, we ask for your continued support in providing tips and information to the Orange County Sheriff's Department", he added. The friend left and came back to the park around 4:00 a.m.to look for Bernstein.More news: INEC Releases Timetable For 2019 General Elections
Bernstein, a sophomore, was planning to major in psychology and later study medicine, the Orange County Register reported his father Gideon Bernstein saying last week.
Bernstein's parents said in a news conference they "want to see resolution" to the case, ABC reported.
Authorities say witnesses said Bernstein met up with a friend and the two drove to Borrego Park, where he got out of the vehicle and went into the park. Bernstein went off alone into the park while his friend waited back in the auto, she said.
Bernstein's phone had stopped functioning and was turned off around 11:30 p.m., Della Donna said. "He didn't have his glasses or his medication".
"It's a great technology", Bernstein's mother, Jeanne Pepper Bernstein, said. "I don't think he planned on this being a long trip and he just disappeared". He was supposed to fly back to the East Coast on Sunday to start classes again.
Valentine said recent rain in California helped authorities locate Bernstein's body but he declined to say how.