GREEN COVE SPRINGS, Fla. -- An internal investigation into the death of a dog while inside a Clay County animal control officer's truck found that the officer did not contribute to the animal's death.

Investigators found that neither action nor inaction by Officer Billy Wilson contributed to the death of "Diamond," a dog he'd picked up roaming a neighborhood last month. County officials said that Diamond and seven other animals were in Wilson's truck while he attended a meeting.

The family alleged their 2-year-old dog died from heat stress. They filed a complaint against Wilson, but a criminal investigation has ended with no charges against him.

The necropsy was inconclusive, but suggested that the death was related to heat stress. The fact that the other animals -- smaller dogs, cats and kittens -- did not die contributed to the conclusion that heat was not responsible for Diamond's death.

During the internal investigation, an experiment was conducted using a dog of similar size placed in the same dog box that Diamond as in and subjected to similar conditions -- one hour in a parked truck with temperature ranging from 82 to 87 degrees.

"When they did the experiment, basically they were trying to see if the dog was going to die or live. That was the only two outcomes they were thinking of this experiment," said Diamond's owner Robert Henry.

Learning of the experiment, a former animal control volunteer has filed a complaint against Bill Bodenweber, Clay County's director of enforcement services, alleging it was intentional animal cruelty.

"That's intent animal cruelty right there. It just went beyond my imagination that they'd do anything like that. I just had to go to the sheriff's office," said Don Rammon.

Bodenweber responded with a statement: "The dog used in the simulation was never in danger and was closely monitored in a controlled experiment with constant monitoring by animal care professionals."

READ THE INTERNAL INVESTIGATION: Death Of Rottweiler In Possession Of Clay County Animal Control