A twice-convicted 94-year-old killer has had his life sentence commuted by a Swedish court, opening the possibility he could spend his final days on the outside.

Born in 1928, Helmer Ljus has repeatedly run afoul of the law over the span of his near century-long life. 

Convicted of his first offence at the age of 19, it wasn't until he was 60 that he committed his first murder, killing a friend with an axe and dousing corrosive acid over another man "for snoring," according to legal news outlet Dagens Juridik on Monday.

Sentenced to 11 years in jail, he was released in the mid-90s but quickly found himself facing another murder charge, which he denied. 

He was convicted and given a life sentence for killing his mobility-impaired neighbour at the age of 71, becoming the oldest person to be handed a life sentence in modern Swedish history, the outlet said.

The Orebro district court said in the ruling, seen by AFP, that Ljus' life sentence should be converted into a 39-year prison sentence, given his deteriorating health.

Having already served 24 years inside, that means Ljus would be eligible for parole in two years.

The court noted that the prosecution didn't oppose converting the sentence, but had requested that the duration of the sentence be set to allow the prison service to plan his release and "facilitate the transition to a life in freedom."

The Swedish National Board of Forensic Medicine had also said that the risk that Ljus would commit further crimes was low, noting that his dementia in essence meant "he was a different person compared to before".

Barring an appeal, the ruling will be made final on March 31.

Public broadcaster SVT reported that since 2009,the earliest he was eligible to apply, Ljus has repeatedly sought to have his sentence converted into a timed sentence, citing his poor health. 

According to the prisoners' rights group Penal Reform International (PRI), while there is no global data on older people in prisons, the proportion of older prisoners was growing in a number of countries.

PRI also notes that people aged 50 or 55 in prison are increasingly designated 'older', compared to 60 or 65 in the community at large, "due to accelerated ageing in prison."