Case was not unique but highlighted need for tighter controls on GPs to regain trust

It takes a great man or an evil one to leave a legacy to the world. Harold Shipman, who transmuted his vocation as a doctor from healer to killer, has changed the way people think about, investigate and record deaths.

Doctors have presented Shipman as a uniquely evil man, whose 30-year murder spree was a one off. But the record shows he was merely the latest in a series of doctors convicted or suspected of murdering their patients.

One of the most famous suspects to escape conviction was John Bodkin Adams, the Eastbourne GP who may have provided the model for Shipman. Bodkin Adams forged prescriptions and also admitted at his trial in 1957 that he had "eased the passing" of some of the elderly women in his care, thought to number up to 400. He was mentioned in 132 of their wills but the jury acquitted him.

The public inquiry into Shipman's case, chaired by Dame Janet Smith, called last July for an overhaul of the coroner's system, with a team of investigators ready to examine any death. The index of suspicion should be raised, she said, and all deaths where medical error or neglect was a concern should be examined.

She also called for tighter controls over death certification and an end to the present system which relied solely on the honesty and competence of a doctor attending a death. It provided few safeguards against dishonest or homicidal doctors and Dame Janet was pointedly critical of those who said there would "never be another Shipman".

Critics, however, fear that Dame Janet has over-reacted, creating unnecessary bureaucracy which will detract from the proper business of doctors - caring for patients. They also maintain that a man as cunning and determined as Shipman would have been able to evade any system designed to stop him.

The biggest mystery, which Shipman has taken to his grave, is why he did it. One of the greatest difficulties for doctors in the modern world is that, having started their careers with hopes of healing the sick, they find there are severe limits to what they can do. Most conditions they encounter in their surgeries are long-term chronic illnesses for which modern medicine has little to offer. Shipman was a man who liked to control those around him and, if he found the limitations of medicine frustrating, he always knew that the syringe of morphine that he carried in his bag gave him the power over life and death that he otherwise lacked.

There may be few ways of stopping a determined killer. But in the final part of her inquiry, due to report this year, Dame Janet has raised doubts about the robustness of mechanisms introduced by the General Medical Council to check on the performance of doctors.

Her intervention has dismayed members of the GMC, which has spent three years winning acceptance for the mechanisms. But her concern reflects the extent to which the Shipman case has undermined public trust in doctors.