If you prefer not to boost, then you should be aware that a large portion of this achievement rests on luck. I can, however give you a few tips:
-In order to get this, it would behoove you to be neck and neck with the leader. I tried to keep myself within 100 pts.
-When it comes down to the last ten seconds, you don't have to necessarily run around and try to kill your target. I got this because my pursuers were actually running around like idiots and I evaded them and hid in a bale of hale and got the last 200pts right before the match ended. Other effective methods would be to smoke and stun your pursuer if you think they're around or lure your opponent into attacking a civilian by using the decoy ability. Killing your target would probably be the most difficult, but obviously, if you get the chance go ahead and kill him.
Again it's mostly a luck based cheevo but there are some things you can do to sway the odds in your favor. Also, I got this in Advanced Wanted.