"This arrogant captain is guilty of attacking many civilian ships and subjecting them to torture. Stop his acts of savagery."
The target is found on Misteriosa. Head to the Viewpoint at that location if possible for an easier time overall. If not, head to the Viewpoint on the island. The target, a Captain, walks a short patrol nearby the viewpoint. When you approach him, he will start off to the West. If you head to the lower tower not too far West from the Viewpoint quickly then you can tag him with a Berserk Dart before he is out of range. Running him down from behind is also an option as is an aerial assassination.