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

Just before 8:30 a.m. on Monday, the 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 they reported him missing on Sunday. 

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

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

The woman also questioned how something like this could happen.

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

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A 39-year-old man’s body 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 reportedly 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 died at a Planet Fitness in Indianapolis has asked the company to enact 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 shared their condolences.

“We were deeply saddened by the passing of one of our members, and the franchise owner is working with the local authorities in their investigation. At Planet Fitness, we have robust operational brand protocols in place, as the safety and well-being of our members is our top priority. We are working closely with our local franchisee to ensure they are upholding those brand protocols,” McCall Gosselin, chief corporate affairs officer at Planet Fitness, said in a statement. 

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

The circumstances of Sink’s death remain under investigation.