Naya Rivera's final moments were spent saving the person she loved most, according to investigators. During a press conference on Monday, the Ventura County Sheriff's Office said they believe the "Glee" actress may have drowned after "muster[ing] enough energy to save her four-year-old son, but "not herself."

Rivera's body was found on Monday, five days after she went missing during a boating trip at Lake Piru with her son, Josey, whom she shares with ex-husband Ryan Dorsey. At the press briefing, Ventura County Sheriff Bill Ayub recounted what Josey told authorities about the tragic accident.

Naya Rivera
Naya Rivera Naya Rivera/Twitter

Rivera, 33, rented a pontoon boat on Wednesday, July 8 and Josey was later found alone and asleep on the boat by another boater on the lake, wearing a life vest and wrapped in a towel. A life jacket, believed to have been Rivera's, was found onboard along with her belongings.

Josey Saw His Mother Disappear Under the Water

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

According to Ayub, there were a lot of currents on the lake that emerged particularly in the afternoon and authorities believe she may have been dragged underwater as a result.

In response to a reporter's question asking how Rivera managed to get her son back onto the boat but not herself, Ayub said she probably used up all of her energy to save her son.

"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," Ayub said at the press conference.

Lake Piru has been the site of several drownings over the years, and the actress's disappearance prompted a petition calling for signs warning swimmers of its dangerous conditions. Days before her disappearance, she shared a touching post with Josey on social media.

Naya Rivera
Naya Rivera last social media post with her son days before her disappearance. Naya Rivera/Twitter