Authorities confirmed Naya Rivera’s death after her body was found in Lake Piru on Monday, July 13. Based on the evidence and what her son, Josey Hollis Dorsey, told investigators, they believe she drowned after getting her son to safety. During a press conference, Ventura County Sheriff Bill Ayub shared details about her final moments.

“We know from speaking with her son that he and Naya swam in the lake together at some point during their journey,” Ayub said. “It was during that time that her son described being helped into the boat by Naya, who boosted him to the deck from behind. He told investigators that he looked back and saw her disappear under the surface of the water.”

Although Rivera’s cause of death has yet to be determined, authorities revealed they have a working theory of what went wrong. “There are a lot of currents on the lake that appear, particularly in the afternoon,” Ayub explained. “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 onto the boat, but not enough to save herself.”

Naya Rivera and Son Josey
Matt Baron/Shutterstock

Josey, 4, was discovered alone in the pontoon vessel Rivera, 33, rented earlier in the day. He was wearing a life vest at the time and was wrapped in a towel. An adult’s life vest was also found on the boat, along with Rivera’s purse, wallet and ID. Authorities believed the former Glee star went swimming without her life vest, which was seemingly confirmed when her body was discovered without it on July 13.

While swimming is allowed at Lake Piru, authorities told Life & Style the waters can be treacherous. “These big reservoirs, there is a lot that goes on. There are plenty of currents,” Captain Eric Buschow, the Ventura County Sheriff’s Office spokesman, said. “People drown in California lakes every year.” Lake Piru, in particular, is known for its “strong winds” and “chilly water.”

Naya Rivera and Son Josey
Matt Baron/Shutterstock

Rivera’s former costars and friends paid tribute to her on social media after news of her death broke. “Rest sweet, Naya. What a force you were. Love and peace to your family,” wrote Jane Lynch, who played Coach Sue Sylvester on the show.

“How can you convey all your love and respect for someone in one post? How can you summarize a decade of friendship and laughter with words alone? If you were friends with Naya Rivera, you simply can’t,” said Chris Colfer, a.k.a. Kurt Hummel. “Her brilliance and humor were unmatched. Her beauty and talent were otherworldly. She spoke truth to power with poise and fearlessness. … Naya was truly one of a kind, and she always will be. Sending all my love to her wonderful family and her beautiful son.”