Staff nurse Colin Norris was jailed for life today for the murder of four patients and told he would serve a minimum of 30 years.
Norris, 32, from Egilsay Terrace, Glasgow, killed the vulnerable women in 2002 by giving them massive doses of insulin while working at two Leeds hospitals.
Jailing him at Newcastle Crown Court, Mr Justice Griffith Williams said: "You are, I have absolutely no doubt, a thoroughly evil and dangerous man."
Norris was convicted of four counts of murder and one attempted murder yesterday following a lengthy trial.
He was given four life sentences with a minimum term of 30 years for each of the murders and a 20-year sentence to run concurrently for attempted murder.
He was described by West Yorkshire Police as "extremely arrogant".
Detectives said he showed no remorse for killing Doris Ludlam, 80, Bridget Bourke, 88, Irene Crookes, 79 and Ethel Hall, 86, while he worked at the Leeds General Infirmary (LGI) and the city's St James's Hospital.
He also tried to kill Vera Wilby, 90, but she survived the coma which followed the unnecessary insulin injection.
Police began an investigation after Dr Emma Ward noticed in November 2002 that Mrs Hall had slipped into a hypoglycaemic coma despite not being a diabetic.
Blood tests showed she had insulin levels 12 times the norm, and she died three weeks later.
Detectives looked at other deaths on the wards from comas when Norris was working and after a lengthy investigation found that by the time Dr Ward raised her concerns, he had already killed three times, and failed with one attempt.
Detective Chief Superintendent Chris Gregg said Norris had been growing in confidence and only the vigilance of Dr Ward prevented his six-month murder spree from continuing.
The nearest the prosecution came to outlining a motive was to suggest that Norris disliked working with the elderly.
All his victims were frail after suffering from hip problems, and they could all be considered a burden to nursing staff.
Norris showed no emotion as he was led away from the dock.
All of the jury members returned to Court 6 today to hear the judge's condemnation of the nurse, whom he believed was seduced by the power of killing.
The judge said: "You are an arrogant and manipulative man with a real dislike of elderly patients.
"The most telling evidence was that observation of one of your female patients, Bridget Tarpey, who said 'He didn't like us old women'."
The judge said Norris disliked the elderly because they needed too much care and he formed the belief that Norris was "essentially lazy".
"Only you know why that dislike was so much that you decided to kill.
"Despite months of evidence, I am no wiser as to your motive."