The Penn E. Dent Prison is a detainment facility in which Colin Devorae was a former inmate.
As the secretary of the Amano Group's CEO Ernest Amano, Devorae had little involvement in the company's dealings with an international smuggling ring. Despite this, when the police began to move in on the company, Devorae was put forward as a scapegoat and was convicted and sentenced to time in Penn E. Dent Prison.
Devorae eventually managed to escape, however, stealing a gun from a guard in the process. The convict fled to Ernest Amano's home, and his former employer agreed to look after him since he had gone to prison on his behalf. Devorae took on the alias "Oliver Deacon" and became the family butler for the next ten years, managing to evade capture completely by the authorities despite their monitoring of the Amano household. His life as a free man was ended when he was murdered by Lance Amano during a failed fake kidnapping plot.
The name "Penn E. Dent" is likely meant to be a play on either "penitentiary" (a state or federal prison for convicted felons) or simply "penitent" meaning someone who is repentant of their crimes. It is also similar to the word "pendant", as in the pendant Devorae broke into two parts; one part for his daughter and the other for himself.