i have met people from my time in the army who couldn't do anything with their lives but serve in the army. Some of those people get jealous at people who are successful both in civilian and military life. Just a thought. Those types of people are everywhere. This should be investigated.
killing your own in afghanistan is very rare, considering the terrain and how the americans operate. There isn't a "huge" operation tempo going on (initial invasion) and large amounts of units coming and going and the passage of lines being done. This is a very questionable situation and I won't lose any sleep if an investigation is done.