UTAH STATE PRISON — It began when an inmate walked up to Julie Cox, cradling a tiny, 4-week-old kitten in his large hands.

"He said, 'They're killing the cats. Can you help out?"' she recalled.

That was her first introduction to a hidden community living behind bars, alongside the inmates — a growing colony of feral cats. It was also the beginning of a program that has successfully reduced the feral cat population here, and seemingly restored some of the most hardened criminals' sense of humanity.

The cats often show up here in the fields surrounding the prison's razor wire fences, dumped and abandoned by people. In the 1990s, many of the feral cats found on prison grounds were rounded up and then euthanized. That seemed to only make things worse.

"Those few cats left start breeding like crazy and over-breed in a vacuum effect," said Holly Sizemore, the executive director of No More Homeless Pets in Utah.

Cox, who works as a substance abuse counselor at the prison's Promontory facility, said she couldn't believe it was happening.

"My initial thought was, 'Why are they killing these animals? They're the innocent ones in the prison,"' she said.

On her own time and her own dime, Cox started doing some research and contacted No More Homeless Pets in Utah, an animal welfare group that has been trying to end the feral cat problem in cities all over the state.

They recommended something called "trap, neuter, return."

"We met with the Department of Corrections and they thought it was a viable option," Sizemore said. "My argument was, you keep removing the cats and they're euthanized. The following year, you have just as many cats if not more cats."

Corrections officials signed off on the idea.

Trap, neuter, return

"Trap, Neuter, Return" is a long-term population control program where feral cats are trapped, sterilized and vaccinated and then returned to their habitat.

The cats wouldn't be here if people didn't abandon them, Sizemore said.

"Unfortunately, people think that grassy areas and any type of open space — there's birds, there's mice, they'll do fine," she said. "Without human assistance these cats don't stand much of a chance. It starts because people aren't spaying or neutering their pet cats."

The program, advocates say, helps control the feral cat colonies by reducing the population over time, allowing the cats to die out on their own, whereas euthanasia has the potential to create over-breeding.