Indianapolis police are investigating after a man was found dead in a tanning bed at a Planet Fitness gym Monday morning, three days after he went missing.

Authorities identified the deceased man as Derek Sink, 39, the Marion County Coroner’s Office confirmed to People.

“This remains an ongoing death investigation,” a county spokesperson told the publication.

Sink’s family told NBC affiliate WTHR that he went into the tanning bed on Nov. 8. His aunt said they reported him missing that same day.

Sink was wearing an ankle monitor, according to his family, which helped authorities discover he never left the gym location. His family claimed he was struggling with a drug addiction and a needle was found in the room with him.

A woman who entered the Planet Fitness on Nov. 11 told WTHR that she and other gym members noticed a foul smell in the building that seemed to be permeating from the tanning rooms.

The Indianapolis Metropolitan Police Department and the coroner’s office did not immediately respond to HuffPost’s requests for comment.

Following Sink’s death, Planet Fitness said it was “deeply saddened by the passing of one of our members.”

“At Planet Fitness, we have robust operational brand protocols in place, as the safety and well-being of our members is our top priority,” spokesperson McCall Gosselin said in a statement to People on Nov. 12. “We are working closely with our local franchisee to ensure they are upholding those brand protocols.”

No cause of death has been determined in the case.