Ok well basically i got this quest from the trader to kill a stalker called "Fiend", easy enough i thought....that was until i noticed where he is. Sat right in the middle of the damn duty base with 2 friends. Well in i go and attempt it, the moment i fire a single round or use my knife that damn siren goes off in the base and everyone goes postal. Is there anyway to actually do this? as even with no witnesses if you kill someone in the duty base the whole place is alerted.
Using a silenced weapon when there's no witnesses should do the trick. However I've had the same thing happening to me once. The moment I killed the stalker everyone in the Duty base attacked me. The guys in the bar were friendly though. I returned an item to barkeep, got a new mission and went back outside. There were 8 Duty guys in my Contacts list when I came out of the bar, only two of them were listed as 'enemy' (while they were all enemies before I entered the bar). I managed to sneak out of the Duty base and finished barkeep's mission. When I returned to him for a reward the whole Duty base was friendly again.
Oh, I also killed quite a few Duty guys after I killed that stalker. They kind of forced me into it :P Must've been at least 30 of em. I think that's what made me first in the rankings