Two Real IRA gunmen pumped three bullets into Daniel McGurk, 35, at his home in the Lower Falls area when he opened the front door.
The father-of-six was murdered less than 24 hours after he had taken a knife and gone hunting for the men who beat him days earlier.
But when he failed to find them, his killers ended the dispute by calling at the Ross Road house and opening fire at around 11am today.
Mr McGurk, who was hit in the chest, thigh and ankle, died later in the nearby Royal Victoria Hospital.
His partner and some of his children were at home at the time.
Even though the shooting took place in the staunchly republican west Belfast, security sources immediately ruled out any Provisional IRA involvement.
Police believe renegade republicans opposed to Sinn Fein leaders Gerry Adams and Martin McGuinness and their support for the Northern Ireland peace process were behind the murder.
Neighbours said a row broke out between Mr McGurk, who was not attached to any organisation, and Real IRA men after he was accused of urinating against a house in the area.
“He got a hammering a few days ago and then he went looking for them ,” said one.
“But they decided to get their retaliation in first and just shot him dead.”
Detectives believe the murder could have been a so-called punishment shooting that went too far.
One said: “Because he was shot in the ankle it may have been one that went wrong.”