William Duell was hanged for rape and murder. He lost consciousness on the gallows and was taken for dead. A few hours later he revived whilst being prepared for dissection by medical students. The authorities took pity on him and commuted (reduced) his sentence to one of transportation (exile) to North America.
This was a time of great developments in the understanding of medicine, in part due to the practice of training medical students through the dissection of dead bodies. There were strong religious and cultural prejudices against dissection, which made dead bodies difficult to find for this purpose. As a result, executed criminals were regularly provided to medical training colleges.