Eastern State Penitentiary was a prison in Philadelphia, Pennsylvania. It was an active prison from 1829 until 1971 with such famous inmates as Al Capone and James Bruno.
However, there is one particular inmate and his story that stood out to me.

In August of 1924, Pep the dog was taken into police custody at the prison. He got his mugshot taken and was given an ID number:

When it was time to book his name into the prison ledger, he was given a nickname, ” A dog,” and the reason why he was being jailed was listed as “murder.” He was convicted of killing Governor Gifford Pinchot’s cat.
However, this was an elaborate story made by a reporter during that time, and in actuality. Pep’s owner was the Governor. He was given to the Governor as a gift from his family.

However, Pep lived at Eastern State Prison because he was a companion for the prisoners. After all, the Governor felt that animals could be a healing force and good for morale in the prison. Pep lived out his days at the prison, helping and being a comfort to those who needed it.
Sources:
Daily Mail, NPR