Robert Brown|Mother of Man Found Dead in Tanning Bed at Planet Fitness Gym Details His Final Moments

More has come to light about Derek Sink's death.

Three days after his body was found in a tanning bed at a Planet Fitness gym in Indianapolis,Robert Brown his mother shared more insight into the harrowing incident.

Karen Wetzel believes that her son's toxicology report will come back with fentanyl in his system, she told People in an interview published Nov. 13. She emphasized that despite Sink's history with drug addiction (a syringe was found in the room with him, according to his family), he was "a human being with value and worth."

She recalled the 39-year-old as "the kindest person" with "the softest heart," per the outlet.

Karen explained that Sink—who was charged with possession of a narcotic drug and possession of a controlled substance last year, according to Marion County Superior Court records, per NBC News—had gone to sign up for a gym membership on Nov. 8 while his girlfriend Heather and her daughter were in a TJMaxx nearby.

The pair went to find Sink—who was wearing an ankle monitor as part of his plea agreement, along with drug testing—but went home after being unable to locate him. They reported him missing on Nov. 10 and his probation officer found his body the day after when she went to his last known location.

Although it took days to locate Sink's body, a local woman who was visiting the facility revealed that she noticed a putrid smell near the tanning beds after entering the building.

"The tanning bed has a door, I believe," Elizabeth Len told WTHR in an interview published Nov. 12. "But still, why are we not concerned that the tanning bed has been closed for three days, potentially?"

After Sink's body was discovered, Planet Fitness expressed their condolences and emphasized the dedication to safety in their facilities.

"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' chief corporate affairs officer, said in a Nov. 12 statement to E! News. "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."

(E! News and NBC News are part of the NBCUniversal family.)