An autopsy report released on Friday revealed new details about the death of Glee actress Naya Rivera, who drowned in July while boating with her 4-year-old son on a California lake.

The investigation from Ventura County Medical Examiner determined that the 33-year-old raised her arm and called for help when she accidentally drowned at Lake Piru northwest of Los Angeles, The Associated Press reported. 

According to the report, Rivera first helped her son, Josey, get back on the boat. The boy then “noticed the decedent put her arm up in the air and yelled ‘help,’” the autopsy stated. The actress "knew how to swim well," but she "disappeared into the water,” investigators concluded.

The man who rented the pontoon boat to Rivera said he put a life vest aboard even though she declined the safety gear.

Medical examiners said Rivera struggled with vertigo and a recent sinus infection. Drugs weren't found to be factors in her death. However, the toxicology report found a small amount of prescribed amphetamines in her system, as well as minimal amounts of an anti-anxiety drug and an appetite suppressant.

Josey, who was found sleeping alone on the boat later that day, was taken to his father. 

As Blavity previously reported, the body of Rivera was found in the lake on July 13, less than a week after she was reported missing. 

"I can't make any sense of what happened," Ventura County Deputy Chris Dyer said after the body was found. "We just know that we found a 4-year-old on a boat, and he said that his mother never got back in."

During the search, officials released surveillance video from the lake's parking lot. The footage showed Rivera and her son walking toward the water on July 8. With use of sonar equipment, as well as help from divers, investigators conducted the search for the missing mother.

After presuming her to be dead on July 9, the search continued until four days later when her body was found floating on the surface of the lake.  

Sgt. Kevin Donoghue said Josey "gave enough information to investigators to conclude that his mother never made it out of the water."

Investigators added that the conditions of the lake posed a challenge.

 “There’s a lot of challenges in a reservoir this size, at times with visibility,” Capt. Eric Buschow told CBS Los Angeles.

According to CNN, the northeast area of the lake, where Rivera's body was found, is 35- 60 feet deep.

The Glee cast member posted a picture of herself and her son a day before she went missing.

"Just the two of us," she wrote. 

View this post on Instagram

just the two of us

A post shared by Naya Rivera (@nayarivera) on

Fans and celebrities went to social media to mourn the loss after learning about the tragedy.

"The story about Naya Rivera is the most horrifying thing I have read about in a while. My heart goes out to her family. What a terrible trauma," wrote Bethenny Frankel, founder of Skinny Girl. 

Sister, Sister actress Jackée Harry recalled a 4-year-old Rivera making her debut on the sitcom, The Royal Family. Harry was hoping for a miracle after the actress went missing. 

“We starred alongside one another in her first very television series, The Royal Family, and I’ve watched her career blossom ever since. Please God, don’t cut this life short,” Harry wrote.

Zack Teperman, Rivera's former publicist, said he was "hoping it isn't true."

"I'm just sad. #NayaRivera was one of the first people I had the honor of working with back in 2009 when I got into public relations and moved to Hollywood," he wrote on Instagram. "One of the first people to allow me to give her advice and guide her through those crazy #Glee days."

View this post on Instagram

I am in complete disbelief and shock right now as I post this. I still can’t believe what I’m hearing and hoping it isn’t true. I’m just sad. #NayaRivera was one of the first people I had the honor of working with back in 2009 when I got into public relations and moved to Hollywood. One of the first people to allow me to give her advice and guide her through those crazy #Glee days & fun yearly Vegas birthday parties. I can’t believe the news right now and waiting for this to just be a god-awful prank of some sort. It’s unfair to take a mom from her young child like this so suddenly. This is terrible. I don’t even know what to say. I am looking back at these images and hoping this isn’t true. Urgh. You will be missed and never forgotten. You helped shape my career and me into who I am today. Thank you Naya. But please, don’t let this be true. ???????? sending my love to your entire family right now!

A post shared by Zack Teperman (@zackteperman) on

Rivera, who played as Santana Lopez on Glee, also starred in the comedy film The Master of Disguise, as well as the television series, Step Up.