Assassin's Bullet (2012) on Netflix

Plot summary

Robert Diggs once worked as a field agent for the FBI. He left that career behind and took a post as the cultural attaché in Sofia, Bulgaria, to escape the memory of his wife's death, which he blames himself for. He works there for Ambassador Ashdown. Then a vigilante begins killing high-priority terrorists whose names sit on America's Most Wanted list, one after another, and the killer's identity is unknown. The FBI and the CIA ask Diggs to take on the case, and Ambassador Ashdown presses him to agree. Diggs has to find out who the killer is before an international incident follows.