John Leonard MacKean died at the Springhill, N.S., facility on Wednesday.
MacKean, 65, was sentenced in Bridgewater Supreme Court on June 24. He got 24 months in prison.
MacKean's crimes date back to September 2012, when the boy, who was 16 at the time, emerged half-naked from the woods. He said he had been chained in a cabin and assaulted by three men. MacKean was arrested in November of 2012 at a Fredericton hotel.
During MacKean’s trial, the teen testified that he was blindfolded with a sleeping mask, and his hands and feet were chained to a bed when a man sexually assaulted him at the cabin in a rural area. He said he had been held against his will for eight days.
The boy told the province's Supreme Court in Bridgewater that a man performed oral sex on him as he cried, unable to move.
MacKean told the jury that when he arrived at the cabin, the teen was not chained and did not seem upset.
MacKean was diagnosed with a heart condition and had special requirements for his health while he was in prison.
DNA found in cabin
During the trial, MacKean denied he performed oral sex on the youth, said he was led to believe the victim was a young adult and that if he felt the youth was distressed, he would have the teen freed.
MacKean said he was invited to the cabin by Wayne Alan Cunningham, with whom he had a sexual relationship after the two met at an Alcoholics Anonymous meetings.
Cunningham invited MacKean to the cabin where the teen was being held.
David James LeBlanc, another accused, was sentenced last June to 11 years in prison after pleading guilty to kidnapping, forcible confinement, sexual assault, uttering threats and breach of conditions.
An agreed statement of facts in LeBlanc's case said he offered the teen a painting job and drove him in a van from Halifax to a cabin in Lunenburg County about 130 kilometres away in September 2012 on the pretext of picking up painting supplies.
The youth later escaped and a woman found him barefoot at her doorstep, chained at his wrists and ankles.
LeBlanc was arrested in northern Ontario in September 2012. Police were also searching at the time for Cunningham, whose body was later found near the area where LeBlanc was arrested. Foul play was not suspected in his death.
The police and the coroner have been notified. Correctional Service Canada says it will review the circumstances of the incident.