SERIAL killer Harold Shipman may have murdered three elderly patients within hours of each other, the inquiry investigating his death toll has heard.

Shipman, who is serving life for the murders of 15 former patients, was the on-call doctor at Todmorden's Abraham Ormerod Medical Centre, West Yorkshire on January 21, 1975.

Many of Shipman's Todmorden patients had links to Burnley General Hospital,

The inquiry heard Shipman had worked late and, according to a colleague, was always "eager" to assist with emergency call-outs.

But in the space of five hours and a few hundred yards he certified three deaths. At 4.10pm he filled out the death certificate of Elizabeth Pearce, 84, before repeating the same process just a few hundred yards away at 7.30pm inside the house of Robert Lingard, 62.

Shipman's last visit was less than an hour later. It is believed that he was called out to 73-year-old Lily Crossley's house by family members who had become concerned about her deteriorating health. She had become agitated and seemed very distressed.

As he left the house he told Mrs Crossley's sister-in-law Margaret Gilyeat that he had given her an injection and that it would calm her down. An hour later she was dead.

Shipman's first visit while on call was to Mrs Pearce, who was suffering from trouble with her knees. She found it very difficult to get around.

Although there are few details regarding her death it is clear from records that Shipman was present and signed the death certificate. Three hours later Mr Lingard was also dead. Although he was not registered with Shipman it was the 55-year-old killer who again signed the death certificate and telephoned the man's immediate family to inform them of the death.

A few months before, Mr Lingard had developed bronchitis and emphysema. His breathing deteriorated and within a short time he could not manage to get up and down the stairs. At about 7.30pm on Tuesday, January 21, 1975 Shipman telephoned Mr Lingard's daughter-in-law Margaret to inform the family of his death. "I was surprised to get the call because it wasn't as if Bob had been in imminent danger," Margaret told the hearing. "I also thought it was very unusual for Dr Shipman to be on a house call so late in the day.

"Dr Shipman told me that Bob had died and asked if we could come to the house."

Less than two hours after death was confirmed, at 7.30pm, Shipman was called out again.

Mrs Crossley had been fairly restless and seemed confused.

Mrs Gilyeat recalled: "When the doctor was leaving he said that he had given Lily an injection and that it would calm her down." One hour later, at around 9pm, she was dead.

The three deaths are among 31 cases being investigated from Shipman's time in Todmorden, dating from March 1974 to September 1975. The inquiry starts again on Thursday.