The man whose body was found Saturday in a truck parked behind the Ooltewah Bi-Lo most likely died of natural causes several days earlier, Chattanooga police said.
There were no evident signs of trauma to the body, and there was evidence of vomit inside and outside the cab. Officers said they found alcohol in the vehicle.
Police believe they know the identity of the 47-year-old man, but can't confirm it until they run fingerprints and notify next of kin.
Police are unsure how long the man has been dead, but it could have been at least two days before anyone noticed, said police spokeswoman Sgt. Jerri Weary.
Someone pulling into the parking lot to get lunch noted a smell coming from the truck and called police, officers said.
It's possible the man was living out of his gold GMC pickup, police said. In the truck's bed were clothes, documents, sneakers and bedding. Sneakers had been wedged in the truck's windows.
The body was sent Saturday to the Hamilton County Medical Examiner's Office for evaluation.