Method to Remove Aliens

I'm doing this in JMS and I can't get it to work. There's an int alien in addition to str, dex and luk and when I try the OP method I end up with the same number of aliens as before. I have seen a map completely cleared of aliens so someone figured it out (in the last seven hours) so I'm doing something wrong.

 Spoiler

1. 1.) Get rid of dex aliens
   
2. 2.) Kill a str/luk alien
   
3. 3.) Let it spawn two more aliens
   
4. 4.) Exit map
   
5. 5.) Wait eight to ten seconds, come back
   
6. 6.) See an "Alien appeared" message
   
7. 7.) Kill the two aliens
   
8. 8.) Somehow there's an extra alien
   

Step 6 seems to be the problem but I'm outside the map for well over thirteen seconds each

 Spoiler

I know I'm necroposting but JMS just got the event ._.