Halo 3: ODST Achievement - Killing things that are new and different is bad/good

When I played through Halo 3: ODST I saw the "squids" and killed them when I saw them, and got a counter (1 of 10, 2 of 10, 3 of 10, etc) toward the achievement Killing things that are new and different is bad. Eventually, like in the scene when I'm in a banshee escorting the phantom through the city, when I would kill the squids, I wouldn't get that counter anymore, so I could never finish the achievement. On the other hand, I never saw ANY reference when I played toward getting the "good" version of the achievement. Can anyone tell me how to accomplish this, or why I might have stopped "getting credit" for my squid kills, and what the difference between the good and bad versions of this achievement are?

Solution 1:

Ok, so the way to get the "bad" version is:

• Only killing Engineers (that's what the squids are called) in the night time story count (ie. where you get the missions from)
• There are ONLY 10 of them
• You can miss one, which the Brutes are killing

To get the "good" version you have to only avoid killing these 10 (ones in the individual missions don't count) and save the one from the Brutes

Here is a map of the 10 engineer locations (and incidentally the audio logs)

I found the map at AchievementHunter.com