He was found deceased on August 22 when police were called to his approved bail address.
Paki said the coroner was responsible for determining the cause of death, but police had advised Corrections there was nothing suspicious about his death.
Bail had been granted for a number of reasons, including his health issues.
As previously reported, Johnstone was seriously injured during the same incident that took Chapman’s life.
The shooting occurred in broad daylight in a popular waterfront reserve. Photo / RNZ, Nick Monro
He was charged with murder while still in hospital on March 4.
Once discharged from hospital, he was remanded to Mt Eden Corrections Facility in Auckland.
He entered a not guilty plea in May and his initial name suppression lapsed that same month.
Johnstone had been refused bail after a previous application, despite his lawyer arguing that Corrections was struggling to manage his injuries.
Chapman’s death rocked Whangārei, both because the 66-year-old was well-known and well-regarded, and because the popular Onerahi beachfront reserve was busy with families at the time.
The shooting occurred just after 11am.
After Chapman’s death, one of her sons posted a heartfelt tribute online.
“She touched the lives of so many with her kindness and love … She was a precious taonga to us and will be terribly missed,” he wrote.
Friends described her as “a beautiful person” who was mischievous and fun to be with.
– RNZ