"He was selecting people who were a nuisance to him. One of the ladies was throwing her bedclothes off her just before he killed her. To him she was an irritant, a nuisance, and for that she died."

Norris, from Glasgow, committed his crimes in 2002 while working in hospitals in Leeds and once said he disliked caring for "geriatric patients".

He was caught when a specialist, Dr Emma Ward, grew suspicious and ordered blood tests on Mrs Hall, 86, after she was found unconscious.

Mrs Hall, who was admitted to hospital with a broken hip, was discovered to have been given 1,000 unnecessary units of insulin, compared to the 50 a day given to someone with diabetes, a condition she did not have.

It prompted a police inquiry into the deaths of 72 patients, which identified 18 suspicious deaths, eight in which Norris the nurse at the point of death.

He was later arrested on suspicion of murdering five women and trying to murder another while clinical explanations were accepted for two of the deaths.

Norris was charged with four murders - Mrs Hall, Doris Ludlam, 80, Bridget Bourke, 88, and Irene Crookes, 79, and one attempted murder, Vera Wilby, 90, after the Crown Prosecution Service considered there were too many complicating medical factors to bring a fifth murder charge.

Post mortem examinations were not conducted in the case of the other two and the deaths were certified as through natural causes.

Prosecuting, Robert Smith QC, told Newcastle Crown Court there were "remarkably common facts" between Norris's five victims, who had all undergone surgery for hip fractures.

Each was in poor health and could be regarded as a "burden to nursing staff", Mr Smith said.

Each suffered from hypoglycaemia between four and 12 days after surgery.

Norris has never revealed a motive for his crime, leading senior detectives to believe he did it simply because he had the opportunity to do so.

Det Ch Supt Gregg said: "What has shone out through this investigation and trial is the absolute dedication of nursing and medical professionals. Colin Norris is an exception to that.

"While others around him were duly caring for their patients, he was looking for opportunities to kill them by poisoning them with insulin.

"He presented himself to police during interview and the court during the trial as an extremely arrogant individual who has not shown the slightest degree of remorse or emotion for what he has done.

"Why he chose to do what he did is only known to him, but it is clear that all hi victims were frail, elderly ladies who were vulnerable in his care.

"Norris is not only a dangerous criminal, but cunning in his actions, choosing times to commit his crimes carefully, being either early in the morning or at weekends when he knew senior and specialist staff were not routinely on duty."

Stuart Hall, 53, a service engineer, called for a public inquiry and also compared Norris to Dr Shipman.

Mr Hall, her son, said: "As the person who injected his victims with insulin, he was the only person who knew what was wrong with them and that gave him the choice if he wanted to administer the antidote and create a miracle revival.

"It gave him the power to give life and to take life. I hope they put him away permanently and never let him out."

Mr Hall added: "Somebody like that is extremely dangerous because they know how to kill discreetly.

"It is very much a Shipman-like thing. It could have been more than five and could yet still prove to be."

Mr Hall said Ethel's widower John had a heart attack three weeks after her death and other members of the family are sometimes too scared to go to hospital.

Dr Hugo Mascie-Taylor, medical director of Leeds Teaching Hospitals NHS Trust, said changes had since been implemented at their hospitals but added that none of the changes could have prevented Norris's crimes.

He said: "These were dreadful crimes that took the victims prematurely from their families. We are very sorry about this and our thoughts today are with the families: for any distress they suffered both at the time of their relative's death and during the course of bringing Colin Norris to justice."

January and September 1999: Norris attends lectures on diabetes and the treatment of diabetic patients with insulin.

May 24 to July 4 1999: While training to be a nurse, Norris works on ward 11 at Ninewells Hospital in Dundee where he learns about the management of patients with diabetes.

1999: Norris cares for elderly patients on ward 7 at the Royal Victoria Hospital in Dundee as part of his training. He tells his tutor he hated the placement and missed part of it through "unauthorised absences".

January 11 2001: Norris's personal tutor gives a specific talk to her students on the subject of abuse of elderly patients, including particular reference to a Glasgow nurse in the 1970s who was convicted - but later freed on appeal - of killing elderly patients by injecting them with insulin.

May 21 2001: Norris works at the Riverside Nursing Home in Dundee caring for elderly people and misses 11 days of the placement. During another placement in 2001 at Broughty Ferry Health Centre, near Dundee, Norris tells a district nursing sister he "didn't like working with geriatric patients".

June 2001: Norris graduates from Dundee University with a Higher Nursing Diploma.

October 2001: Norris starts work as a staff nurse at Leeds General Infirmary where he works on ward 36. During the next 14 months he also works on the orthopaedic ward at St James's Hospital in the city.

May 2 2002: Vera Wilby, 90, is admitted to ward 36 at Leeds General Infirmary with a broken left hip after a fall in Rawdon, Leeds. Her condition deteriorates as she recovers from surgery.

May 17 2002: Norris administers a dose of the powerful painkiller morphine to Mrs Wilby to make her drowsy. He then administers more drugs and 90 minutes after he finishes his shift at the hospital, she is found semi-conscious with a sudden hypoglycaemic attack but survives.

June 12 2002: Doris Ludlam, 80, from Pudsey, West Yorkshire, suffers a fall and breaks her hip at Chapel Allerton Hospital in Leeds where she is receiving treatment for a heart complaint. She is transferred to ward 36 at Leeds General Infirmary for surgery.

June 16 2002: Bridget Bourke, 88, of Holbeck, Leeds, is admitted to ward 36 at Leeds General Infirmary with a broken right hip.

June 17 2002: Surgeons operate to repair Mrs Bourke's hip. She is frail and confused, with bleeding in her head and complications from a stroke and she also develops a serious bacterial infection.

June 25 2002: Norris gives Mrs Ludlam an "unnecessary" dose of the powerful painkiller diamorphine, which is double the recommended level. This renders her drowsy and Norris then gives her drugs which reduce her blood sugar level before he goes off shift at 7.45am. She is discovered in a coma about 40 minutes later.

June 27 2002: Mrs Ludlam dies.

July 20 2002: Mrs Bourke falls out of bed.

July 21 2002: Norris, who is working the night shift, claims to have discovered Mrs Bourke slumped in bed at 3.10am. Doctors are called and she is found to be deeply unconscious after a hypoglaecaemic attack, despite not being diabetic.

July 22 2002: Mrs Bourke never recovers and dies shortly after midnight. The death certificate records the cause of death as from a stroke.

October 2002: Mrs Wilby is discharged from hospital and goes to live at a nursing home. She dies the following year from unrelated causes.

October 10 2002: Irene Crookes, 79, from Hunslet, Leeds, falls and fractures her hip and is treated on ward 23 at St James's Hospital. Norris treats her for several days and, although she remains unwell, breathless and requiring oxygen, and needing a walking frame to get about, her condition is giving no undue cause for concern. Norris records in her notes that her condition is improving.

October 19 2002: Norris reports finding Mrs Crookes "totally unresponsive" shortly before 6am. She has suffered a hypoglaecaemic attack but is not diabetic.

October 20 2002: Mrs Crookes dies.

November 2002: Ethel Hall, 86, of Calverley, Leeds, is admitted to ward 36 at Leeds General Infirmary with a fracture to her hip and undergoes surgery to repair it. All goes well and she appears to be recovering, being able to walk with assistance.

November 19 2002: Ethel Hall has fainting spell, which is not unknown for her.

November 20 2002: Ethel Hall takes a "very serious turn for the worse" in the early hours of the morning and staff find her choking. Her blood sugar levels are found to be very low and blood tests show abnormally high levels of insulin.

Earlier in the evening, Norris predicts this change in condition, without any medical indications, in a conversation with colleagues, saying: "Whenever I did nights someone always died." He continues: "It was always in the morning when things go wrong - about 5.15am."

December 6 2002: West Yorkshire Police are called in to investigate.

December 11 2002: Ethel Hall dies of irreversible brain damage without ever regaining consciousness.

December 2002: During questioning by the police, Norris tells officers "he seemed to have been unlucky over the last 12 months" but denies murdering his patients.

September 2003: 14 months after her death, Mrs Bourke's body is exhumed by detectives investigating Norris. A pathologist finds that she died from an insulin-induced coma.

October 12 2005: Norris is charged with four counts of murder and one of attempted murder.

October 16 2007: Norris goes on trial at Newcastle Crown Court charged with four counts of murder and one of attempted murder.

March 3 2008: Norris is found guilty of murdering Ethel Hall, Doris Ludlam, Irene Crookes and Bridget Bourke. He is also convicted of the attempted murder of Vera Wilby.

Telegraph.co.uk

A year after the lecture, Norris’s campaign of murder began adopting the same method - using insulin - and later he even copied McTavish who allegedly predicted the minute that a patient would die.

Norris was born in Glasgow 32 years ago to his namesake father, a painter and decorator, and his mother June, who worked as a typist.

The paradox of his pathological dislike of elderly patients was that the person he had been closest to in his life was his grandmother.

As an only child, he became particularly close to Elizabeth Ogilvie, who is in her late 70s, after his parents divorced when he was nine years old.

She refuses to accept he could be the killer of four woman pensioners, saying: “He can’t have done it, not my grandson, not my boy.”

Later in his life, Norris would tell a colleague that he did not like bathing female patients - “especially because they were the same age as my grandmother”.

He grew up in the city’s Partick area and saw little of his father after the matrimonial split, Mrs Norris remarrying four years later.

Mother and son went to live with her new husband Raymond Morrison, also a painter and decorator, and his young son, in the next street to her mother in Milton, Glasgow.

Norris served as a boy scout and helped look after mentally handicapped people while also becoming involved in amateur dramatics.

At secondary school he passed six standard examinations, Scotland’s equivalent of GCSEs, before going on to college to study travel.

He left the course after a year to work in travel agencies before deciding to train as a nurse when he was 22.

Norris said he made the career switch because “you get to deal with people and get to make a difference in their lives.”

He studied for a Higher Nursing Diploma at Dundee University’s School of Nursing and Midwifery and also had two part-time jobs.

His first contact with elderly patients came during a placement on Ward Seven at the Royal Victoria Hospital, Dundee, in 1998.

Norris complained to a friend that he was unhappy because he did not like geriatric patients - he preferred the excitement of trauma work.

He was also sent to the Riverside View Nursing Home in Dundee, but reported in sick with a sore throat after three days and never returned to complete the planned four week stay.

He told a colleague: “When I was bathing female patients and washing them down below I found it difficult to start with, especially because they were the same age as my grandmother.”

During the three year course, Isabella McLafferty, his personal tutor, recalls having to warn him about his attitude and poor attendance.

It was she that on January 11, 2001 gave a specific talk to her students on the subject of the alleged abuse of elderly patients, including particular reference to the case of Sister McTavish.

She was from Glasgow, Norris’s home city, and her trial caused a sensation three decades ago, although the conviction was later overturned.

As a trainee nurse Norris also worked Ward 11 at Ninewells Hospital, Dundee, where he learned about managing patients with diabetes.

While there he repeatedly refused to change patients or their bedding.

Police have found no evidence to suggest he harmed any of his charges during his student years.

But four months after qualifying he obtained a job as a staff nurse on Ward 36 at Leeds General Infirmary and a six month killing spree followed.

Norris was openly gay, spoke in a strong Scottish accent, wore thick black-rimmed glasses and is also remembered for nipping through the fire escape for a cigarette during night shifts.

He had no criminal record and shared accommodation with other men while living in Leeds.

His first attempt to kill a patient in May 2002 failed when 90 year old Vera Wilby survived because the insulin overdose was counteracted by her naturally high blood-sugar level.

Like the others victims to come, she was frail, vulnerable and in poor state of health both before and after undergoing surgery to repair a damaged hip.

Her quality of life was diminished and she was a difficult patient to care for.

At the end of one of Norris’s night shifts she was found by medical staff in a hypo-glycaemic state, her brain being starved of sugar.

She survived the attack but was the only one to do so.

Norris refined his killing technique before murdering Doris Ludlum, 80, in June 2002.

In the early hours of June 25, Norris gave her an “unnecessary” dose of the powerful painkiller diamorphine, which was double the recommended level.

This rendered her drowsy, and then before he went off shift at 7.45am, Norris injected insulin, which reduced her blood sugar level.

Forty minutes later she was discovered in a coma and she died two days later.

A month later Bridget Bourke, 88, died of the same hypo-glycaemic condition on Norris’ watch, and then Irene Crookes, 79, in October.

All the woman had been injected with massive insulin overdoses, even though they were not diabetics so did not need the drug, as they recovered from routine hip operations.

On each occasion, the deaths were put down to natural causes – and Norris’s confidence grew.

He told a colleague “someone always died” when he was on the nightshift and was said to have become so arrogant that he accurately predicted his next death, that of Ethel Hall, to within 15 minutes.

After she was found collapsed in a coma, Norris pointed to his watch and said to a staff nurse: “I told you so”.

Another former colleague said that Norris seemed to react with “detached amusement” when the women died, while two ex-patients claimed Norris verbally abused them after they rang an emergency buzzer on a ward when an elderly patient climbed out of bed.

They said he told them: “I hope you suffer” and “rot in hell”.

A total of 72 deaths were investigated by police as part of the investigation and 18 were classified as high priority before he was charged with the four murders and attempted murder.

Detectives believe he used the opiates to make his victims drowsy before injecting them with the lethal dose of insulin.

Police recovered documents detailing a less painful way of injecting morphine or diamorphine.

The prosecution said it was impossible to say what the motive was, but all the patients had been difficult and were capable of being a burden to medical staff.

He was suspended by the Royal College of Nursing the day after his arrest on Dec 11 2002. While on bail, he moved back to Glasgow, worked for an events company and travelled abroad eight times while under investigation.