Hello
I'm no scripiting expert, but what I DO know is that to make the enemy dissappear in the players face you can do this:
In the
level editor when you have placed the grunt on the level, click on him, go to the tab called "Entity" and check the small box saying "Hallucination". Under there you can select how close the monster must be to the player before dissappearing. BE AWARE that if it's too close, the monster might be able to hurt/kill the player before he disappears.
Hope it helped atleast a bit. You could do like I do, look around on other threads and see if someone else has a slightly similiar problem or such.
Hope you get it to work!
-Rokotain