If anyone except your squad mates see you - you get detected, everyone turns hostile. use your other mercs to distract everyone. The problem is - this "visibility" in my experience sometimes crosses walls even, so look around for that special AI, who sees you, walk/run/sprint (noisy
) with some merc away from action, then all the AI's look at him, and your'e free to kill him.
Similar tricks were needed in at least two other cases
