Toxicologist Julie Evans told Preston Crown Court that tests revealed levels of the drug consistent with samples from people who died of a morphine overdose.

Healthy people die within five minutes if 30 milligrams of morphine is injected into their veins, the jury heard. And pain relief expert Professor Henry McQuay said an injection of the drug dissolved in water would make a person not suffering from pain sleepy.

Describing the symptoms, he said within minutes their breathing would slow down until it stopped, their lips would go blue and as no oxygen could reach the brain they would die.

Mrs Evans told the court that varying amounts of the drug were found in samples taken from the thigh and liver of wealthy widow Kathleen Grundy.

Excessive morphine was found in Kathleen Grundy's body

Tests at the laboratory in Chorley, Lancashire, showed Mrs Grundy, 81, had one microgram of morphine per gram of thigh muscle and two areas of the liver showed the presence of the drug.

Mrs Evans said the samples were relatively well preserved, although Mrs Grundy died on 24 June 1998.

When asked by prosecuting QC Peter Wright whether "Kathleen Grundy had taken or been given a substantial amount of morphine or diamorphine", Mrs Evans said: "Yes, I would agree with that."

She also said her findings were "entirely consistent" with levels that are seen in other deaths attributed to excessive doses of morphine.

The scientist added that death, decomposition and the process of embalming, would not increase the levels of morphine found.

The jury heard that samples taken from alleged victims Bianka Pomfret, Winifred Mellor, Joan Melia, Ivy Lomas, Marie Quinn, Irene Turner, Jean Lilley and Muriel Grimshaw also revealed morphine.

There was no scientific evidence for the other six alleged victims as they were cremated.

Dr Shipman, 53, of Mottram, Greater Manchester denies killing 15 female patients and of forging Mrs Grundy's £400,000 will.