Detectives re-examining the 1984 Wellington Trades Hall Bombing have been collecting DNA samples from suspects.
The police have always struggled to pinpoint a motive for the bombing and numerous investigations over the years have failed to find the person responsible.
But the cold case has been reopened and the police have recently revealed more details about the bomb's components - including that it was wrapped in a 1977 edition of The Evening Post.
On Tuesday, 27 March, 1984, Wellington Trades Hall caretaker Mr Abbott was locking up for the day.
At 5.19pm he picked up a suitcase which had been left unattended for several hours. The movement triggered a bomb and Mr Abbott was killed almost instantly.
Police believe the explosive was equivalent to three sticks of gelignite. The force of the explosion was considerable and required a detailed scene examination.
Mr Abbott was the sole victim of the attack and despite numerous investigations, police have always struggled to identify a motive for the bombing.
Why are police reviewing the case?
Police have revealed details of the suitcase bomb's components and its construction in the hope it will jog someone's memory.
One relatively uncommon component, a mercury switch, was part of the device. When Mr Abbott moved the suitcase the mercury tipped, connecting the circuit and detonating the bomb.
The bomber set a 60 minute stove timer, which gave sufficient time for the bomber to take the device to the Trades Hall and deposit it.
Police believe there were two bottles of accelerant in the suitcase. One was a popular Teal brand soft drink bottle containing petrol and one was sealed with an Asti Riccadonna cork.
The forensic profile of the bomber prepared in 1984, described the offender as a loner, possibly a hoarder who had difficulty maintaining relationships, was angry and fixated, had experience with explosives and held a grudge against the union movement.
This article was first published on Radio NZ.