Mary Mara, best known for her performances in ‘ER’ and ‘Criminal Minds’, died at the age of 61 on Sunday. Authorities confirmed that the actor died of asphyxiation due to drowning.

“The Jefferson County Medical Examiner’s Office performed a post-mortem examination on the decedent and determined that the decedent’s manner of death was an accident, due to asphyxiation, due to warm water drowning,” NYSP Troop D Public Information Officer Jack Keller told PEOPLE.

Her body was found on Sunday in St. Lawrence River in New York’s Cape Vincent. 

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Investigators believe the 61-year-old may have slipped and hit her head while getting out of the river. This may have caused the actor to fall back in and drown, TMZ reported. 

“The preliminary investigation suggests the victim drowned while swimming. The victim’s body showed no signs of foul play,” PEOPLE quotes police as saying. 

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Mara acted in shows such as Criminal Minds, Nash Bridges, NYPD Blue and Law & Order. She was also seen in Star Trek: Enterprise, Lost, Dexter and Shameless.

Confirming the actor’s death in a statement to PEOPLE on Sunday, her manager, Craig Dorfman, called her “one of the finest actresses I ever met.”

“I still remember seeing her onstage in 1992 in Mad Forest off-Broadway. She was electric, funny, and a true individual. Everyone loved her. She will be missed,” Dorfman said. 

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In her obituary, shared by PEOPLE, her family praised her as “a gifted character actor.”

“Her 32-year career in film and television resembled that of a veteran utility infielder who just missed stardom but always played for winning teams,” it reads.