Harold Shipman is currently the subject of The Shipman Files: A Very British Crime Story, which takes a look at the serial killer's victims - and how he managed to go undetected for so long.
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Harold was eventually caught after suspicions arose when one of his deceased patients had left him a great deal of money in her will, but a taxi driver, John Shaw, had suspicions about the doctor long before that.
WATCH: Harold Shipman is the subject of The Shipman Files
The driver previously spoke about his guilt for not going to the police after he noticed that his elderly customers, who he often drove to the hospital in good health, died under the care of Harold Shipman.
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Speaking in the public inquiry into Shipman's crimes back in 2003, he said he felt guilty as "at least 20 people died because I had no one to turn to or speak to". He added that he didn't report his suspicions because he thought they were "crazy and fantastic".
He explained: "I did consider getting in touch with the General Medical Council, but I think I was put off because there had been lots of scandals in the medical profession and I had no confidence they would investigate Shipman."
© Photo: RexJohn opened up about his suspicions in 2003
John added: "The fact that Shipman was such a well-respected figure in the community who seemed to be popular and well-liked by his patients made it more difficult to express my concerns publicly. I couldn't believe what my suspicions were. They were so fantastic that I couldn't grasp what my mind was telling me."
© Photo: RexHarold is thought to have murdered up to 250 patients
Shipman was given a life sentence for the murder of 15 patients, while it is thought that he killed up to 250 throughout his career. He died in 2004.
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