An investigation is underway into what led to the death of a man whose body was found in a tanning bed three days after entering a Planet Fitness in Indianapolis.

Just before 8:30 a.m. Monday, Indianapolis Metropolitan Police Department received a report of a body found at Planet Fitness.

The Marion County Coroner’s Office identified the man as 39-year-old Derek E. Sink.

According to police records obtained by 13News, Sink’s family last had contact with him on Friday and reported him missing on Sunday.

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A man was found dead inside a Planet Fitness in Indianapolis. (Michael Nagle/Bloomberg via Getty Images/Getty Images)

Police could only confirm to Fox News Digital that they are investigating a death at the gym and did not elaborate on the details of the investigation.

A woman who was at Planet Fitness Monday morning told 13News that she and other members noticed a foul odor in the building that got worse near the tanning rooms.

The woman also wondered how such a thing could happen.

“The tanning bed has a door, I think, but still, why aren’t we concerned that the tanning bed has been closed for potentially three days?” Elizabeth Len asked.

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The body of a 39-year-old man was found in a tanning booth at an Indiana Planet Fitness, according to multiple reports. (Raymond Boyd/Getty Images/Getty Images)

Sink’s family told 13News that he struggled with drugs and a needle was found in the room with him, while his aunt told the news station he was wearing an ankle monitor that helped investigators determine he never left the gym.

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The family of a man who was found dead days after he passed out at Planet Fitness in Indianapolis called on the company to adopt stricter policies with an end-of-day checklist. (Don Emmert/AFP via Getty Images/Getty Images)

Planet Fitness released a statement to Fox News Digital confirming the death and offering its condolences.

“We are deeply saddened by the passing of one of our members and the franchise owner is working with local authorities in their investigation. At Planet Fitness, we have robust brand operating protocols as our safety and well-being. members is our top priority. We work closely with our local franchisee to ensure they adhere to these brand protocols,” said McCall Gosselin, director of corporate affairs at Planet Fitness.

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Sink’s family also told 13News they hope to see stricter cleanliness policies and an end-of-day checklist from staff to prevent this from happening to another family.

The circumstances of Sink’s death remain under investigation.