Trackers, also known as Bounty Hunters are people who are in the business of tracking others. Given the state of universal governments, and the ease with which anyone can cross galaxies, law enforcement has had to adapt by outsourcing resources where possible. A lot of this is done by way of private security firms, but even they have a limited jurisdiction. Those who need a longer reach use Trackers.
Most Trackers find work on jacklists just like Freejacks do.