After 10 years in jail Johnstone was released, but remained on parole for life.
He was recalled three times for violence, and was most recently released in May 2016.
But in April he was arrested and recalled in relation to a violent incident with his partner’s 17-year-old son.
Johnstone was found guilty on one charge of threatening to kill following a judge-alone trial in the Invercargill District Court in September.
The court heard Johnstone was angry as he believed the victim owed him money and cigarettes, so showed up to an Invercargill address where he and his mother were.
The victim’s evidence was that the murderer had stolen a caravan key and he chased after him to get it back. He claimed Johnstone yelled that he would kill him and later picked up a brick.
The victim said he reacted by arming himself with a shovel, but Johnstone claimed the teen had picked up his weapon first.
The court heard at trial that the 17-year-old hit Johnstone in the head with the shovel, causing him to become dazed and stumble, ending the altercation.
Text messages following the incident showed the defendant calling the boy a “dead man walking” and said the teen would join his late father “one way or another”.
Judge Duncan Harvey convicted and discharged the defendant on one charge of threatening to kill and acquitted him on all other charges.
Initially, Johnstone also faced two charges of assault with a weapon, two charges of possessing weapons and a further charge of threatening to kill.
“I simply do not know to the required standard who did what when,” Judge Harvey said.
Counsel Roger Eagles said his client had completed courses to prevent this kind of violence.
“Clearly very unsatisfactory behaviour from the defendant,” he said.
Last month Johnstone saw the Parole Board, which was not willing to release the inmate as he remained an “undue risk”.
“It is serious for Mr Johnstone to threaten to kill this young man given he was on parole for murder,” the parole decision said.
“Mr Johnstone’s risk arises primarily from domestic situations, and so he will need a safety plan that focuses, while not exclusively, but significantly on such risk.”
The board requested a psychological report and a copy of Judge Harvey’s trial decision before Johnstone’s next hearing in May.