Ontario Provincial Police said Robert Frank Conroy, 19, was found with serious injuries in a cell block at Collin’s Bay Institution in Kingston on June 7, 1982. He later died in hospital.
OPP spokeswoman Sgt. Kristine Rae said new information led to the arrests, but declined to elaborate on what the information was.
Rae said investigations into prison deaths face significant roadblocks.
"When you are dealing with a penitentiary-type situation it becomes much more difficult. They have their own code within the walls of the penitentiary which makes it difficult for investigators to get information," said Rae.
One of the accused, Robert Simpson, 50, was transported from a provincial institution in Montreal to Kingston and charged with first-degree murder. He is expected to appear in court in Kingston on Thursday.
Winnipeg police arrested Jeffrey David Peck, also 50, and charged him with first-degree murder. He is being returned to Kingston and is expected in court on Friday.
Police are asking anyone with information about the case to contact them at 1-888-310-1122.