Nurse Colin Norris was jailed for life on Tuesday after being found guilty of murdering four elderly patients with lethal doses of the diabetes drug insulin.
Norris, 32, from Glasgow, was told he will serve a minimum 30 years in jail.
He gave the drugs to four women during his time at two hospitals in Leeds in 2002.
He was also found guilty of the attempted murder of another woman, and was sentenced to a minimum 20 years to run concurrently.
Police said after the verdicts at Newcastle Crown Court on Monday that he had targeted "frail, elderly women, generally confused and helpless" whom he regarded as difficult.
Detective Chief Superintendent Chris Gregg said he would have killed again, had not a doctor on the ward became suspicious.
Dr Emma Ward ordered tests for insulin on one of the women who had lapsed into an unexpected coma.
They showed about 12 times the normal level of insulin in her blood.
Norris was found guilty of murdering Ethel Hall, 86, from Calverley, Leeds, Doris Ludlum, 80, of Pudsey, Bridget Bourke, 88 - whose body was exhumed for tests - and Irene Crookes, 79, of Leeds.
He was also found guilty of the attempted murder of Vera Wilby, 90, of Rawdon.
