Before disappearing in a California lake, Glee star Naya Rivera used her last strength to save her 4-year-old son by boosting him onto the deck of their drifting boat. And according to officials, she did not have the energy to save herself.

Ventura County Sheriff William Ayub told reporters, “We believe it was mid-afternoon when she went swimming, the idea being, perhaps, that the boat began drifting… and that she mustered enough energy to get her son back on the boat but not enough to save herself.”

The press conference was held after the discovery of the 33-year-old actress's body on Monday. He added, “[Her son Josey] described being helped into the boat by Naya, who boosted him onto the deck from behind. He looked back and saw her disappear under the surface of the water.”

Rivera’s body was found floating near the surface in the northeastern corner of Lake Piru about six days after she went missing on Wednesday.

Citing the location and clothing of the body and the fact that no one else has been reported missing in the lake, Ayub said at a press conference, “We are confident the body we found is that of Naya Rivera. There are a lot of currents on the lake that appear particularly in the afternoon.”

On Wednesday afternoon Rivera’s son Josey Hollis Dorsey, from her marriage to actor Ryan Dorsey, was found asleep on the pontoon, wrapped in a towel and wearing his life jacket.

Naya Rivera was found near where the pair had gone swimming. The area of the lake goes 35 to 60 feet deep with heavy bush and trees rising nearly 20 feet from the lake bed.

Ayub said, “We believe she was concealed within the shrubbery of some of the floor bed of the lake” before the body rose to the surface.

The remains looked like they had been in the water for several days and did not have a life jacket. An adult-size life vest was found on the boat. Also, there was no indication of foul play or suicide.