The prosecutor, Richard Henriques, QC, told the GP he had referred to possible drug abuse in false computer records he had created for Kathleen Grundy to explain why morphine would be found in her exhumed body.
Dr Shipman, 53, of Roe Cross Green, Mottram, near Hyde, denies killing 15 women patients and forging Mrs Grundy's pounds 386,000 will. He is alleged to have killed Mrs Grundy with an injection of diamorphine in June last year and forged the will to leave him as the sole beneficiary.
Mrs Grundy was found dead in her home in Hyde, Greater Manchester, less than four hours after Dr Shipman visited her to take a blood sample. The GP, who certified death as due to old age, said in his seventh day in the witness box at Preston Crown Court he now accepted her death was from morphine poisoning.
"It follows she had it administered or took it herself some time between when I saw her and when she was found dead," he said. He had never prescribed diamorphine - clinical name for heroin - for Mrs Grundy, a former mayoress of Hyde.
Mr Henriques asked: "Did you contemplate the sensible possibility that she had got into her motor car and driven to some drug dealers, obtained diamorphine, driven home and administered it to herself?"
Dr Shipman replied: "I don't think it's my role to ascertain where the diamorphine came from the she had taken."
Mr Henriques said: "I suggest that your attributing a drug habit to Mrs Grundy is quite wicked." Dr shipman replied: "If that's what you want to do that's fine. These records were made at the time and were accurate."
He was asked why he had said to nurse Marion Gilchrist before his arrest that "I read thriller books and I would have me guilty on the evidence". Dr Shipman said: "It was a piece of black humour. I was being put under suspicion for an action I had not done. Of course, if you looked at it from the police side there was reasonable evidence to make it that I had killed Mrs Grundy."
He said he accepted the forged will and a letter with it had been typed on a typewriter from his surgery, which Mrs Grundy sometimes borrowed.
"I could see that the police would go very hard and enthusiastically to get me. It was black humour that explains the comment, so I could survive the next two weeks before I was arrested."
He agreed he was crying and "very upset" when he made the comments. Mr Henriques said: "If you were upset that's not very humorous."
Dr Shipman replied: "Black humour by definition is not very humorous. I wouldn't want anybody to think I had committed a murder when I hadn't committed a murder."
Mr Henriques asked if he could think of anybody else who would have wished him to have Mrs Grundy's estate. Dr Shipman said: "I can't think of anybody unless Mrs Grundy took it into her head that's what she wanted to do."
Mr Henriques: "Are you suggesting Mrs Grundy forged her own will?"
Dr Shipman: "I am not suggesting that."
The trial was adjourned until Monday.Reuse content