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 ._.

Actually the first time we were given aliens they came in tons, we were given it too early before part 2 was released but, when it came out there were tons. There was no way possible that you could remove those tons of aliens that came flying out. After they removed the aliens and release it with part 2 finally, they lowered the spawns and spawn rates. This method probably works with the lowered and fixed spawn rates, I don't know how its like over at JMS.

For the most part, it helps a lot if you picked a ch and map with the least amount of spawns. Some people suggested to give some time to the map first before starting the removal, but I'm not 100% sure on whether you'd need to do that or not. The "Alien appeared" msg means that the map just spawned another scout alien that can bring more aliens out so it really means that something did not work right. Whenever you see that message it really means another alien just appeared in the map so thats the main thing you're looking for.