A dog began his sentence at Eastern State Penitentiary on this week in Philly history

Only in Philadelphia can a dog go to prison, let alone serve a life sentence.

On Aug. 31, 1924, Pep the black Labrador retriever arrived at Eastern State Penitentiary in Fairmount.

A prison that housed all sorts of dangerous characters had added a dog to its list of famous inmates, which included serial bank robber (and mostly unsuccessful prison escapee) Willie Sutton. Pep even overlapped with gangster Al Capone.

Pep’s crime?

While not quite substantiated, the legend has it that this innocent-looking pupper was a vicious cat murderer.

Pep the pup was accused of killing then-Gov. Gifford Pinchot’s prized feline, according to the Daily News. The Pike County sheriff took the canine to Eastern State, the newspaper reported. Details about the cat — which some news reports said belonged to the governor’s wife — and what exactly happened to it remain murky.

Anyway, Pinchot then sentenced Pep, who was owned by the governor’s neighbors, according to an Inquirer article, to life in prison.

And Pep was taken to what was then one of the most advanced prisons in the world. The penitentiary at 22nd Street and Fairmount Avenue opened in 1829 as the first institution designed to hold all prisoners in total isolation, a regime called “the Pennsylvania system.”

Prison administrators and politicians around the country quickly recognized the troubling effects of long-term isolation, long before Eastern State abandoned the practice around 1913.

So Pep’s arrival in 1924 was a welcome sight to the residents of the prison. Despite his sentence, he was more pampered than punished, rising to become a beloved and much-enjoyed mascot to the incarcerated.

Rumors that dog was simply donated to the prison by the governor as a way to help boost inmate morale appear to be true. The group that runs Eastern State said there was “solid evidence — including letters preserved at the Library of Congress and multiple newspaper articles — that the ‘cat murdering’ account was a joke.”

“Governor Pinchot did donate Pep to Eastern State to help boost morale, following the example of the Governor of Maine,” spokesperson Nicole Frankhouser wrote in an email.

Regardless, Pep was assigned inmate No. C2559, and sat like a good boy for a standard mug shot.

Guilty or not, in prison Pep stayed and died six years later, or 42 in doggy years, in 1930, according to the Daily News.

He was buried on the prison grounds, and a marker was later placed on his final resting place, according to the Daily News. But Frankhouser noted that if there were a marker, it would have been set at Graterford Prison, not Eastern State.

“One newspaper account notes that prisoners were never told of Pep’s death,” she added, “but rather that he had been transferred so as not to cause unrest.”