Douglas Bruce Scott was discovered dead in his cell on July 5, 1985.
A subsequent coronial hearing, police investigation and Royal Commission into Aboriginal Deaths in Custody all concluded he had died by self-inflicted hanging.
But Mr Scott’s widow, Letty Scott, refused to accept the findings and worked tirelessly to bring murder charges against two Berrimah prison guards.
A civil action was launched in the Northern Territory’s Supreme Court, and Mr Scott’s body was exhumed in April this year for a new autopsy.
However, Justice David Angel ruled that the circumstances of Mr Scott’s death remained inconclusive.
He said that while he could not determine if the prisoner died by self-inflicted hanging, there was no evidence to show he had been murdered.
“I can comfortably conclude that the plaintiffs have not established to my satisfaction that the deceased was murdered by the defendant prison officers,” he said.
Barry Medley and Michael Lawson, the two prison officers named in the trial, said they welcome the judgment.
“On 5 July 1985, we performed our duties as best we could,” the men said in a joint statement.
“We have had to go through a lot to have Mrs Scott’s allegations heard and determined by the Supreme Court. The Court’s ruling is a welcome and final determination.”
But the judge did criticise the initial handling of the police investigation.
According to a report by ABC Radio National, Justice Angel said officers failed to check Mr Scott’s cell for footprints or fingerprints and did not take statements from two fellow inmates who claimed to have heard suspicious noises from his cell.