Orville Lynn Majors, 38, who reportedly told a colleague that old people ''should all be gassed'', had been linked to 130 deaths.

But he was only tried on the seven cases the prosecution thought most likely to secure a conviction. Majors was found guilty on six of those counts last month.

A victim's relatives embrace each other after the sentencing

"It's the judgement of this court that the maximum sentence is the minimum sentence in this case," said Judge Ernest Yelton.

Relatives of Majors' victims broke down in tears as he was sentenced to 60 years for each of the six murders.

Judge Yelton described Major's crime as "a paragon of evil at its most wicked".

"He was entrusted with these people's care. In response he committed diabolical acts that extinguished the frail lives of six people," the judge added.

'He hated old people'

The patients, four women and two men aged 56 to 89, died between 1993 and 1995 at the Vermillion county hospital in Clinton, Indiana.

Prosecutors said Majors gave his victims fatal overdoses and that some of the injections were witnessed by their loved ones.

Investigators said he used the potentially heart-stopping drug potassium chloride, vials of which were found in his home and car.

During the trial a former roommate, Andy Harris, testified that Majors told him he hated old people and said "they should all be gassed".

Majors, who denied the charges, argued that the patients had died from natural causes.

Suspicion fell on the former nurse in 1995 when a supervisor noticed a higher death rate in the intensive care unit during his shifts.

Officials commissioned studies that linked Majors to 130 out of 147 deaths at the hospital.

But the judge ruled that the prosecution could not tell the trial jury about the other deaths.