Police Say Investigation into Naya Rivera's Disappearance Points to 'a Tragic Accident'
"There was nothing that we learned from her son that would have suggested that this was suicide," Ventura County Sheriff’s Office Sgt. Kevin Donoghue tells PEOPLE
Rivera's 4-year-old son Josey was found alone and sleeping aboard a boat at Lake Piru in Ventura County, California, on Wednesday. On Thursday, the Ventura County Sheriff's Office announced that "investigators believe Rivera drowned in what appears to be a tragic accident."
Speaking with PEOPLE on Friday, Sgt. Kevin Donoghue said that at this stage, authorities believe Rivera's disappearance was accidental.
"We interviewed her son and there was nothing that we learned from her son that would have suggested that this was suicide. Everything that we've learned so far leads to this being some sort of water recreational accident," he said.
"To say definitively what actually happened, we really can't say. We just don't know, it's a mystery," he continued. "We're still investigating, we're still searching. We're trying to uncover clues as we go. But so far, we really don't have a lot of information to make any guesses as to what could have happened."
He noted that Friday's search includes more advanced technology, such as a scanning sonar, which "paints pictures of the lake bed floor." He explained: "When it sees an anomaly, an object that's consistent with the shape and size of what we're looking for, then we send divers to search that specific area." Donoghue said three such devices are being used to search for Rivera's body.
The conditions of Lake Piru, though, have complicated the mission, making it difficult to see anything deep in the waters due to sediment from the lake bed.
"The conditions aren't like they are in the ocean, where you can have some places really clean, clear water. In lakes, typically the closer you get to the bottom of the lake, the less visible it is," Donoghue said. "So if she's resting at the bottom of the lake, she's probably resting somewhere where there's zero visibility."
Following the discovery of the pontoon on Wednesday, Josey told investigators that his mother did not get back in the boat after being in the lake. It is unclear if Rivera put him back in, or if Josey climbed up himself.
"I know she was in the water. I don’t know if she helped him back on the boat," Donoghue said. "That I don’t know."
"He gave us enough information for us to conclude that she is still in the lake somewhere," Donoghue told PEOPLE on Friday.
"My investigators are speaking to the family. They're saying he's doing as good as he can under these circumstances," he added. "Given his age, I don't think he fully understands everything that's going on. But his family, their family, they're heartbroken. This is an absolute tragedy."