January 14, 1946 - January 13, 2004: Age 57
Dr. Harold Shipman was one of the most successful serial killers in history. He was an English doctor who dispatched an estimated 250 of his patients by giving them overdoses of heroin, and then forging medical records to make it seem they were already in poor health.
In 1998, a colleague became uneasy at the number of cremation forms he was asking her to countersign. She felt sure that he was somehow killing his patients, but she didn't know how, so she approached the district coroner with her suspicions. An initial police enquiry did not produce enough evidence for charges. A few months later he killed a woman for whom, bizarrely, he produced a will cutting out her own children and leaving a tidy sum to him. Her daughter went to the police, who had the dead woman's body exhumed: it showed traces of heroin. When Shipman was arrested it emerged that his own personal typewriter was used to make the fake will.
In January 2000 he was convicted of killing 15 of his patients; a further inquiry after he was sentenced to prison for life concluded that he was probably responsible for about 250 deaths, including that of a four-year-old girl. Because he was usually the only doctor to sign the death certificates, and because many of the patients were cremated, it would be difficult to know for certain. He never spoke about his actions and although in one case there was a will, in most of the other cases there was no clear motive. He did steal jewelry from some of his victims, but not systematically.
On January 13, 2004, Harold Shipman was found dead in his cell, hanged using bed sheets tied to the window bars of his cell. He had told his probation officer that he was considering suicide so that his wife could receive a pension; she would not have been entitled to one if he had died after the age of 60. January 14, 2004 would have been his 58th birthday.
Sources: Wikipedia, The Sun