LAKE VILLA, Ill. (CBS) — An autopsy has determined that a man who died after being found unconscious in Petite Lake in unincorporated Lake Villa was the victim of a drowning.

At 5:45 p.m. Friday, the Lake County Sheriff’s Marine Unit and Sheriff’s patrol deputies were called to the 38800 block of North Cedar Crest Drive in unincorporated Lake Villa, and learned that a 49-year-old Round Lake Beach man had gone underwater while swimming in an area called the Sandbar in Petite Lake.

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Deputies found the man’s friends performing CPR on him, and the Marine unit tried to shock the man’s heart back into rhythm by using an automated external defibrillator. Paramedics rushed the man to Advocate Condell Medical Center in Libertyville, where he died.

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On Sunday, the Lake County Coroner’s office conducted an autopsy on the man, identified as Victor Lopez. Preliminary results indicate he died of a drowning, and toxicology results were pending Sunday night.

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“We have been in close contact with Mr. Lopez’s family and our deepest condolences go out to them during this difficult time. This is truly a tragedy,” Lake County Coroner Dr. Howard Cooper says in a news release.