A coroner has ruled that convicted murderer Rufus Marsh collapsed and died of a heart attack while mowing lawns inside Whanganui Prison in January 2010.
Marsh had been in jail for more than then 20 years for murdering Diane Miller in her Wellington home in 1986.
He was previously convicted of manslaughter after an elderly man was beaten to death in Wellington in 1974.
Prison staff gave Marsh CPR before an ambulance crew arrived but could not revive him.
One month earlier, the 53-year-old had reported chest pain.
Coroner Carla na Nagara's report cites Marsh's obesity, his smoking and a family history of cardiac problems as factors contributing to his death.
She also found failures in conveying Marsh's health information between Waikeria and Whanganui prisons, but says the death cannot be blamed on the lapse.
The Coroner's report notes that Marsh had spent only 18 months out of prison since he was 14 years old.
