A small bomb exploded beneath the driver's seat of a car near Belfast Saturday, killing the Protestant driver and engulfing the vehicle in flames.
The bomb went off as Glen Greer, 28, drove away from his home in Bangor, 15 miles east of Belfast, making him the first victim of a political killing in Northern Ireland in three months.
Greer, who crawled from the burning vehicle but died later in a hospital, may have been targeted in a feud involving one or more of Northern Ireland's four pro-British Protestant paramilitary groups.
Two of the groups are represented at multiparty negotiations on Northern Ireland's future, which resumed last month.
Bangor is a past feuding ground where one paramilitary commander was gunned down by disgruntled comrades in September 1995.
The pro-British paramilitary Ulster Volunteer Force denied any involvement in Greer's killing. The other three groups made no comment.
The Irish Republican Army, which draws support from militant Catholics, has been sticking to a 14-week-old cease-fire. The IRA rarely has mounted operations in the Bangor area, which is heavily Protestant and home to many soldiers and police.