Detectives investigating the Harold Shipman murders are considering a further 29 deaths.

It brings to 175 the number of people police believe may have been killed by the GP.

Shipman was sentenced to life for the murders of 15 elderly patients in Hyde, Greater Manchester, by injecting them with diamorphine - the medical name for heroin.

No-one knows exactly when Shipman began killing patients.

But Greater Manchester police believe the 29 deaths under investigation could be linked to the 15 cases of which Shipman has already been convicted.

They are already investigating another 131 deaths, which they revealed after his trial.

It would make Shipman Britain's biggest mass murderer.

The new cases have come to light after people contacted police since the trial, worried about the deaths of their own relatives.

Medical records

Shipman was caught following the death of Kathleen Grundy in June 1998, when her daughter, Angela Woodruff, suspected her mother's will had been forged.

It is the only known case in which Shipman attempted to benefit financially from killing.

Three months earlier, doctors at a surgery in Hyde had raised concerns about the number of cremation certificates Shipman had been asking them to countersign.

But a police inquiry was dropped because of lack of evidence.

At the same time police decided to investigate the deaths of more than 130 of Shipman's other patients. They examined old medical records and questioned surviving relatives.

All of those so far identified as victims of Shipman were women, either middle aged or elderly, mostly widows who lived alone.