Speaking during a press conference, Ventura County Sheriff, Bill Ayub, said: "Her son described being helped into the boat by Naya, who boosted him onto the deck from behind. He told investigators that he looked back and saw her disappear under the surface of the water."
"There are a lot of currents on the lake that appear particularly in the afternoon," he went on. "We believe it was mid-afternoon when she disappeared. The idea perhaps being that the boat started drifting, it was unanchored, and that she mustered enough energy to get her son back into the boat, but not enough to save herself."
On Wednesday, the Ventura County's medical examiner released details of Nivera's autopsy, confirming that the cause of death was accidental drowning.