“We don’t suspect any crime,” said Per-Arne Eriksson at Värmlands police told the Aftonbladet daily.

The man, who was convicted for triple murder in 1975, had been on remand since August after being found with the deceased woman.

The man was found by staff at the psychiatric clinic where he was being housed while on remand on suspicion of murdering.

According to Aftonbladet the man died from a heart attack.

The man was arrested on August 6th after neighbours had become suspicious and police arrived at the apartment to find the woman stabbed to death.

The man had also sustained knife wounds.

The couple had lived together in the apartment for over 30 years and had not previously courted any attention, managing to keep the man’s grisly past a secret from the neighbours.

Following the man’s arrest it emerged that he had previously been convicted for the triple murder of his then fiancée and her parents in December 1975.

The murders occurred after the man complained that the Christmas ham had been under-cooked by his fiancée, according to Aftonbladet.

The man was reported to have been a member of the A9 officers’ club in Kristinehamn at the time and used his service weapon to commit the killings.

The fiancée’s then 10-year-old daughter was also seriously injured in the attack, and the killer was sentenced to psychiatric care.