It's really very simple.
The kill is awarded to whoever does the most damage to you.. NOT who actually did you in.
So vanscrew put a few rounds in you... then broke off and went to land.
Someone else came along and finished you off, but since vanscrew did more actual "damage" (as far as amount of ammo hits) he's the one who got awarded the kill...
so likely vanscrew was touching down on the runway at the time you were actually killed.
Make sense?