The actor’s 4-year-old son was discovered alone in the boat they had rented on Lake Piru, in the Los Padres National Forest, on Wednesday afternoon, CBS Los Angeles reported.
The mother and son had been swimming, and Rivera never returned to the vessel, the boy reportedly told investigators.
Drones, dive teams and helicopters scoured the reservoir for the 33-year-old actor on Wednesday. On Thursday, law enforcement said that they believe Rivera drowned and that the search is now a recovery operation, CNN reports.
“We’re presuming that an accident happened and we’re presuming she drowned in the lake,” Ventura County Sheriff’s Deputy Chris Dyer said at a news conference, per CNN.
Rivera had posted a photo of herself and her son on social media shortly before her disappearance. Her son, who was asleep and wearing a life vest when he was found, is “in good health,” according to the sheriff’s department.
Multiple teams continued to search for Rivera’s location on Thursday afternoon, the sheriff’s department said on Twitter.