Peter Sullivan entered prison at 29 years old, convicted of murdering 21-year-old Diane Sindall. He left at 68, after DNA technology unavailable in 1987 proved the semen found on Sindall's body wasn't his. Sullivan maintains he confessed only after being beaten, denied food and sleep, and threatened with rape charges. His case is now Britain's longest known wrongful imprisonment—and the real killer remains at large.