Allitt could have been stopped at the beginning

EVIDENCE of Beverly Allitt's murderous attacks on her patients was missed because post-mortem examinations of her four victims were not conducted with expert rigour. She could have been under suspicion after her first assault, but the local coroner refused to order an expert autopsy.

Allitt killed Liam Taylor, aged seven weeks, on 23 February 1991. The subsequent autopsy failed to solve what Liam's doctor and the Grantham Hospital general pathologist agreed was 'a medical mystery', according to Nick Davies, whose two-year investigation of the murders, Murder on Ward Four, is published tomorrow by Chatto & Windus.

Liam suffered a fatal heart attack. There was no evidence of heart disease. Charith Nanayakkara, the consultant paediatrician who treated him, arranged for David Fagan, a specialist paediatric pathologist based in Nottingham, to conduct a second post-mortem. Thomas Pert, the Grantham coroner, refused to authorise the second autopsy, which would have cost about pounds 170. Mr Pert, a solicitor, declined last week to comment.

'Further research was ordered and then delayed indefinitely,' Mr Davies said. 'This consisted of sending tissue, organ and other samples for analysis. Four months later, police found the samples sitting in a fridge in Lincoln hospital, still awaiting examination.'

Autopsies conducted on Allitt's three other murder victims reached the wrong diagnoses, Mr Davies said. Tim Hardwick, 11, was said to have died from status epilepticus - an epileptic fit. It is not a cause of death, and Tim had not suffered a fit for more than four hours before the moment on 5 March when, the jury at Nottingham Crown Court decided last week, Allitt gave him a lethal injection.

Becky Phillips, aged nine weeks, died from a huge insulin injection. She was Allitt's seventh assault victim. The pathologist diagnosed sudden infant death syndrome - cot death.

The trial heard that tests discovered the presence of clear cells in Becky's liver, evidence of insulin poisoning. But the hospital was less able to unearth evidence of the murders because it had to rely on inexperienced locum general pathologists - the first of whom emigrated to Australia. The consultant pathologist had died six months before Allitt began her attacks, and appointment of his successor was 'lost somewhere in a bureaucratic pipeline', Mr Davies said.

'The locum had no experience of the established pattern of deaths on the children's ward. And he was not informed of Becky's symptoms during the evening before her death, which were inconsistent with cot death.'

Claire Peck, 15 months, was the 13th and last patient attacked by Allitt. The post-mortem examination was conducted by a second locum pathologist. Claire's doctor, Nelson Porter, urged him to look for signs of foul play. Suspiciously high levels of potassium had been found in her blood. The diagnosis was that she had died from an asthmatic attack.

Pathologists and paediatricians contacted by the Independent on Sunday confirmed shortcomings in hospital management which led to failure to notice clues of criminality. Professor John Emery was consulted by police investigating the Allitt attacks. A distinguished paediatric pathologist based at Sheffield University, he said the coroner's decision not to order a specialist post-mortem examination of Liam Taylor was 'ludicrous'.

'Any paediatric pathologist would have been alarmed by Liam's death. If a paediatric pathologist had been in at the beginning, suspicions would have been much higher, much earlier.

'In each of the other cases, the diagnosis made was not sufficient as a cause of death - there had to be some other factor. When we were consulted, we found things incompatible with the diagnosis.'

The Department of Health is understood to be worried about shortcomings in the system of financing coroners' courts. The Royal College of Pathologists is also urging reform.

A senior forensic pathologist said: 'I can see how diagnosis was missed in the first Allitt murder, but suspicions should have been alerted earlier.

'A coroner pays pounds 57 for a general post-mortem examination, but up to pounds 170 for a specialist. With some coroners, you'd think the money was coming from their own back pockets.'