Heyl met his accomplices Andre Stander and Lee McCall in 1977, while they were in prison together (Heyl had been sentenced in 1977 for an earlier string of bank robberies); Stander and McCall escaped from prison in August 1983, and broke Heyl out in October of that same year.
The three then began a crime spree, which ended in late January 1984 when McCall was killed in a shoot-out with police. Stander, who had travelled to America, likewise died in a shoot-out with police there in mid-February 1984.
Heyl, who had traveled to the Greek island of Hydra shortly before McCall's fatal encounter with police, then travelled to England, where he committed further robberies. These led to his arrest and, in 1985, he was tried at Winchester Crown Court and sentenced to nine years in a British prison.
At the end of his British sentence, he was extradited to South Africa, and re-imprisoned on charges pertaining to the Stander Gang robberies.