Francis Michael Fahey was jailed for 25 years in September 2005 after being found guilty of murdering Jasmin Crathern in August 2002 and New Zealand-born Julie McColl six months later.
Fahey stabbed the two inner-Brisbane sex workers with a bayonet he kept under the front seat of his ute.
The trial jury was told Fahey admitted to police "I obviously stabbed them but I don't recall at all", and "I've spent all my f***ing life saving lives and now I'm taking them and I don't know why".
Queensland coroner Terry Ryan this week found Fahey died aged 70 on April 18, 2023 after being transferred from prison to a Brisbane hospital due to shortness of breath.
"Mr Fahey had been diagnosed with metastatic melanoma in March 2023," Mr Ryan said in his findings.
"Mr Fahey died of natural causes as a result of metastatic cancer with ischaemic heart disease also considered to have contributed to his death."
Mr Ryan had directed police to investigate Fahey's death after he was found lying on his back on the hospital bed, covered in hospital sheets and blankets.
"No medical equipment was attached to Mr Fahey and no signs of trauma or any indications of a suspicious death were observed," Mr Ryan said.
A one-day inquest found Fahey received adequate health care and other inmates, corrective services and the hospital did not contribute to his death.
Fahey's murders led Queensland to close a legal loophole that prevented him from being returned to jail after a failed appeal in a separate case.
He was able to kill Ms McColl in Brisbane in February 2003 when he should have been in jail.
The Industrial Court was not able to issue an arrest warrant after it dismissed his appeal against WorkCover fraud.
Police were subsequently unable to arrest Fahey even after he handed himself in.