Top loyalist William 'Mo' Courtney has been convicted of head-butting a grieving woman during a confrontation over drugs.
He assaulted Tracey Coulter at a government-funded community centre in west Belfast, a judge ruled.
Courtney, 50, from Fernhill Heights in the city, had denied carrying out the attack in July.
It happened after Ms Coulter went to the Lower Shankill Community Association offices to speak to one of his associates about the suspected drug-related death of a relative.
Her cousin Neil Orr had died a week before the incident.
Belfast Magistrates' Court heard a row broke out at the centre between Ms Coulter and another man, David Coleman.
She said Courtney then intervened and head-butted her.
The defendant, who was previously jailed for his role in the 2003 killing of UDA man Alan McCullough, claimed no assault took place.
He stated that he was at the back of the offices at the time and did not even see Ms Coulter.
But District Judge Amanda Henderson agreed with a prosecution contention that the victim would then have been unaware he was in the building.
She also held that Ms Coulter would have no reason to make false allegations against Courtney when her issues were with Coleman.
On that basis she found the defendant guilty of common assault, aggravated by the victim being a woman.
Courtney, who was in court with a friend for the verdict, showed no emotion as he left.
Judge Henderson asked for reports to be prepared before she passes sentences in January.