Josey was found asleep and wearing a lifejacket by another boater on the lake. The 4-year-old was reported to have told investigators that Naya went swimming in the water but "did not come back up" to the boat.
In a press conference, the captain of the Ventura County Sheriff's Department, Eric Buschow, said there was "no evidence of foul play". He added: "We're going on the belief that she did go in the water, and we've not been able to locate her. This may well be a case of drowning."