When the High Court judge, Dame Janet Smith, opens the public inquiry into the crimes of Harold Shipman she will be charged with discovering why the Health Service dramatically failed to detect his crimes earlier.

The inquiry, which is due to open next month, will be charged with examining all of the deaths of the former GP's patients in "suspicious circumstances" during a 24-year career in which alarmingly high death rates went undetected and Shipman was allowed to practise despite a conviction for obtaining pethidine by deception.

Relatives of Shipman's victims have fought hard for a public inquiry.

Ministers had originally wanted to conduct an inquiry into his crimes in private, headed by Lord Laming, a former Inspector of Social Services, but the decision was thrown out last month when relatives won a judicial review of the plan.

After reading Prof Baker's report into Shipman's murderous career some weeks ago, the British government decided to establish a public inquiry led by Dame Janet under the Tribunals of Inquiry (Evidence) Act 1921 which will enable her to compel witnesses to give evidence.

In addition to her examination of the deaths of Shipman's patients, Dame Janet will have the power to ask for any documents from relevant statutory bodies and health authorities in connection with the deaths of his patients.

Throughout his career, Shipman found it incredibly easy to cover his tracks.

He altered patients' records, he was able to stockpile large quantities of morphine he was prescribing to elderly patients - more than any other doctor in Britain - and disguise it by ordering large numbers of all drugs for his practice.

And because he worked alone, death certificates were sent to other GPs for a second signature without independent colleagues ever having seen the body.

The Manchester police team charged with investigating the case never doubted the chilling extent of Shipman's crimes. It investigated 192 deaths among Shipman's patients at his surgery in Hyde, Greater Manchester, before its inquiry was scaled down.

The investigation team also prepared prosecutions in the cases of 23 other patients, including Mrs Alice Kitchen (70), originally from Carrick-on-Suir, Co Tipperary, but the Crown Prosecution Service decided further prosecutions were not in the public interest.

The inquiry will also investigate the conduct of the General Medical Council (GMC), the profession's regulatory body, which failed to act against Shipman when he was convicted on drugs charges in 1975 and argued it was powerless to suspend him when he was being investigated for murder in 1998.

But the public inquiry has been asked to move far beyond the minimum essentials of death certificates and accumulating drugs.

The GP system will be examined in minute detail and the pace of reform within the profession, which has traditionally preferred self-regulation, will be increased to improve the quality of work and level of clinical monitoring in practices.

The government's scheme of reform includes compelling GPs to take part in clinical audits, assessing their performance against other GPs and regular appraisals.

Health authorities would have the power to suspend doctors if it was felt they could be a danger to patients.

Public confidence in GPs has suffered since the Shipman trial last year and complaints to the GMC reached over 4,000 last year compared with 3,000 in 1999.

The increase has reflected growing dissatisfaction with the profession and, in the absence of further prosecutions, the public inquiry into Shipman's crimes is likely to strengthen the government's hand in pushing through reforms, many of which were being resisted by the GMC and the Royal College of General Practitioners.