Domenic Perre, the man charged over the bombing of the National Crime Authority office in Adelaide in 1994, has been found guilty of an unrelated assault charge after spitting on a police detective.
In Adelaide Magistrates Court on Tuesday, Perre was found guilty of aggravated assault over the incident at the Adelaide Remand Centre in 2018.
Two detectives had gone to speak with Perre over an alleged assault on him by another prisoner.
But when the cell door was opened and one of the officers stood in the doorway and called his name, Perre turned over on his bed, raised his head and spat on the sergeant's clothing.
He had previously indicated to prison officers he did not wish to speak with police.
Delivering his verdict on Tuesday, Magistrate John Fahey said he was satisfied beyond reasonable doubt that Perre had assaulted the officer, knowing that he was acting in the course of his official duty.
"I do not have any doubts about the evidence of the two prosecution witnesses," the magistrate said in his reasons.
"I consider they were credible and reliable. I accept that the incident occurred as they stated."
Counsel for Perre, who declined to give evidence, had argued that he was placed at a disadvantage because there had been no forensic examination of the handkerchief the officer had used to clean off the spit or the jacket on which it landed.
The officers were also cross-examined over their failure to obtain any CCTV footage of the incident and a failure to arrest Perre at the time.
But Mr Fahey said the prosecution case did not depend on an examination of the handkerchief and jacket and the evidence of the police witnesses was sufficient to support a finding of guilt.
Perre will be sentenced for the assault at a later date.
Last year he went on trial over the NCA bombing after pleading not guilty of the murder of Detective Sergeant Geoffrey Bowen and the attempted murder of lawyer Peter Wallis.
Justice Kevin Nicholson, who conducted the trial without a jury, is considering his verdicts.
