2-124 was designed to be a Uulshos justice droid, but was reprogrammed to function as an Imperial assassin.
During a Rebel Alliance mission, 2-124 was taken into custody. The Alliance sought to extract any valuable information stored within him via interrogation. However, before a thorough examination of its memory could commence, the droid killed a multitude of Alliance personnel and successfully fled.
Alliance Intelligence's tracking of 2-124 ceased after its escape, with only intermittent reports of its reappearance to assassinate specific Alliance figures. As the Alliance transformed into the New Republic, General Airen Cracken placed 2-124 on his private New Republic Intelligence list of the fifty most threatening entities to the New Republic. This inclusion was based on the assumption that the droid possessed sufficient programming complexity to comprehend the change in government.