A taxi driver who suspected his elderly customers were being murdered by Harold Shipman did not report the killer GP to police because he feared no-one would believe him.
The inquiry has reported Shipman killed 215 of his patients
John Shaw told the Manchester-based inquiry into the mass murderer he thought his ideas were "fantastic", but he could not forget them because the deaths seemed too sudden.
Mr Shaw told the fourth part of the inquiry, called "Whistleblowing", he still felt guilty "that at least 20 people died because I had got no-one to turn to or speak to".
Mr Shaw, a taxi driver in Hyde, Greater Manchester, from 1988 to 1998, said he would have felt able to go to an independent body if one had been in place.
"I did consider getting in touch with the General Medical Council but...I had no confidence they would investigate Shipman," said Mr Shaw.
Mr Shaw, now retired, took a number of the serial killer's patients to appointments at the GP's surgery in Hyde.
"They became my friends," he said.
"Then relatives would ring me and say 'Go
and pick up my mum, she is dead'.
"I was asking who was their doctor? The thing that made me suspicious was that they had all been in good health prior to their deaths."
Mr Shaw said he first had concerns in March 1995 following the death of Netta Ashcroft.
After another patient, Millicent Garside, died in October 1996, Mr Shaw was
told by her son Keith that Shipman had given her an injection.
"I wanted to say 'He's murdered your mum'," Mr Shaw said.
He felt he would not be believed and his wife Kathleen advised him to keep
quiet in case he was wrong and could be sued for libel.
"The fact that Shipman was such a well-respected figure in the community...made it all the more difficult to express my concerns publicly," he said.
"They were so fantastic I couldn't grasp what my mind was telling me. I was equally frightened of being right as I was of being wrong."
Mr Shaw eventually contacted police in August 1998 with concerns over the
deaths of 21 people who had been patients of Shipman, before the GP was jailed for life in January 2000.