The mother of an Indianapolis man who was found dead in a Planet Fitness tanning bed is remembering his final moments.

Derek Sink’s body was discovered at the gym franchise on Hardegan Street on the morning of Monday, Nov. 11. Sink first got into the tanning bed on Friday, Nov. 8, the Indianapolis Star reported. He was 39.

On Wednesday, Nov. 13, Sink’s mother, Karen Wetzel, spoke with PEOPLE about his last days as his family copes with the shocking loss.

“It’s not easy at all. Everybody’s a mess,” Wetzel says. “I’m just trying to keep myself together until this funeral is done, and then I’ll have my fall apart.”

Wetzel says Sink went to Planet Fitness to get a gym membership on Friday. His girlfriend Heather and her daughter were with him and stopped at a nearby TJMaxx. They returned to the gym and couldn’t find Sink, who was wearing an ankle monitor, and thought he might have left. They went to the parking lot and noticed his car was still there. However, it had been moved over one spot from where he originally parked.

This is when Heather and Ava first believed something was wrong, Wetzel tells PEOPLE. They searched for Sink and looked in Planet Fitness and a nearby strip mall, but couldn’t find him. They went home and Sink’s grandmother also called them wondering where he was. After they could not locate him, they reported him missing on Sunday, Nov. 10.

Sink’s probation officer went to his last known location, Planet Fitness, on Monday, and they found her son in a tanning bed, Wetzel says. She questions why it took days for her son to be found, noting that a gymgoer reported a foul smell inside the facility.

Wetzel also alleges that Sink was navigating drug addiction and a syringe was found in the room with him. She says she is convinced when the toxicology comes back, authorities will find fentanyl in his system.

She says that despite Sink’s troubled past, he was “a human being with value and worth.”

Taking a moment, Wetzel remembers her late son as “the kindest person,” with “the softest heart.”

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Sink, who was also the father of a 20-year-old son, tried to turn his life around and worked at a halfway house to help those living with mental or physical issues, Wetzel recalls of her “beautiful” son.

“This remains an ongoing death investigation. The Marion County Coroner’s Office (MCCO) will determine the exact manner and cause of death,” an Indianapolis Metro Police Department spokesperson earlier told PEOPLE on Nov. 12 about Sink’s death.

“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,” McCall Gosselin, Planet Fitness’s chief corporate affairs officer, shared a statement with PEOPLE on Nov. 12. “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.” 

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