Answer:

assailant

AnswerCrossword Clue
ASSAILANTPerson in the shadows, in many mysteries
ASSAILANTBushwhacker
ASSAILANTAttacker
ASSAILANTCop's quarry
ASSAILANTAggressor of a sort
ASSAILANTThug at work
ASSAILANTGoon at work