National Crime Authority bomber Domenic Perre has been jailed for life for the "violent, barbaric and ruthless" 1994 Adelaide attack.
Perre will be in his mid-90s before becoming eligible for parole and will likely die in prison, a just outcome, relatives of his victims and police say.
The bearded 65-year-old had one arm in a sling and sat with his head down as Supreme Court Justice Kevin Nicholson on Friday sentenced him to life behind bars for the murder of Detective Sergeant Geoffrey Bowen and the attempted murder of lawyer Peter Wallis.
With Perre already serving time for drug offences, Justice Nicholson extended his existing non-parole period by 30 years and seven months.
That means the 65-year-old will be aged over 95 before being able to apply for release.
"The murder of Geoffry Bowen and the grievous harm caused to Peter Wallis was violent, barbaric, and ruthless," the judge said.
"Your conduct was brutish. That is totally devoid of any human sensibility.
"It was not just premeditated but intricately devised and planned over a lengthy period of time and was executed in cold blood."
Justice Nicholson said the attack struck at the heart of the criminal justice system and the targeted murder of a serving police officer, acting in the course of his duty, could not be tolerated.
Sgt Bowen died at the scene from extensive injuries, including the loss of his left arm, when a parcel bomb built and sent by Perre exploded in his office.
Mr Wallis, who was standing nearby, lost an eye and suffered severe burns in the blast.
He died in 2018.
Handing down his guilty verdicts in June this year, Justice Nicholson found that Perre had built and sent the bomb and had intended to kill Sgt Bowen or anyone else who happened to open the package.
The device was set with a micro-switch which, once opened, closed an electronic circuit, causing the instantaneous explosion.
Perre was first charged with murder soon after the bombing but the case against him was dropped six months later because of a lack of evidence.
He was arrested again in 2018 after a two-year joint investigation by a number of state and federal authorities including the Australian Criminal Intelligence Commission.
Prosecutors argued the bombing was a personal attack on Sgt Bowen.
They said Perre's hostility towards him had grown because of their interactions following the seizure of a multi-million dollar cannabis crop in the Northern Territory in August 1993.
In handing down his sentence, Justice Nicholson said he took into account Perre's age, health issues, including a heart condition and diabetes, and that he had been living under suspicion for almost 30 years.
"The fact you are almost 66 raises two competing considerations," the judge told him.
"On the one hand, you are highly likely to spend your last years of life in prison.
"Ever present to your mind, this will be a very depressing prospect and one that will leave you without hope."
But Justice Nicholson said Perre had also been able to live perhaps his "best years" in the community free from conviction and punishment.
After watching from the public gallery, Sgt Bowen's widow Jane Bowen-Sutton said the sentence had finally "given justice to our beloved Geoff and Peter Wallis".
"Although our loss is immeasurable, this outcome goes towards bringing a quiet acceptable to our tragic loss," she said.
"We hope that our beloved Geoff can now rest in peace."
Genevieve Wallis, the daughter of Mr Wallis, said Perre's jail term was both justice and retribution.
"This sentence allows our families to move forward," she said.
In earlier defence submissions, Perre's lawyer Gilbert Aitken said his client sympathised with the families of the victims but maintained his innocence.
He has lodged an appeal against his convictions.
