Authorities said Saturday the search for Naya Rivera continued for the fourth day. The 33-year-old "Glee" actress went missing while on a lake with her 4-year-old son in the Los Padres National Forest in Ventura County this week.
CBS Los Angeles reports search crews were expected to continue to use side-scanning sonar technology and cadaver dogs as they look for Rivera across Lake Piru, which is more than two miles long and 130-feet at its deepest point.
Captain Eric Buschow of the Ventura County Sheriff's office said the side-scanning sonar technology provides crews with a detailed image, which then allows them to "focus on specific things rather than putting divers in the water when they are feeling around because they can't see."
Crews focused on the northern part of the lake on Saturday. The search began to wind down shortly before 8:30 p.m. local time and is set to resume Sunday morning, the Ventura County Sheriff's office announced.
Rivera and her son took to the water in a rented pontoon boat back on Wednesday. Hours later, her son was found in the boat alone wearing his life jacket.
Investigators do not suspect foul play; security video shows the pair being the only two people aboard.
"We don't know if she is going to be found five minutes from now or five days from now," Buschow said.
Authorities said Thursday that they believe Rivera drowned in "what appears to be a tragic accident, and said the search and rescue effort had turned into a search and recovery effort, with Rivera presumed dead.