Jan was a freelancing mercenary working for Roberts.
Season 4[]
Jan was first seen in the basement of a building talking to his friend Gregor about the type of bullets they should use for their next job. A few minutes later, Roberts and Vaughn appeared and he introduced him to the team. Roberts briefed the team that they needed to steal an important artifact and to be careful, because it could break easily.
Jan was also seen when Michael decided to brief the team himself and that the job should be done his way, not Roberts'. The team geared up and hijacked the armored truck, stealing the device. While they were escaping, Marcus spotted the group and one of Vaughn's partner (either Jan or Gregor) opened fire, much do his dislike. In the ensuing firefight, Jan was killed by Marcus or the accompanying APO agent.