Oh lord, there are spoilers in this message.
If you do not want to spoil anything in the Mass Effect game, redirect yourself here:
LinkJust speculating here, in the ending where you allow the Citadel Council to die, and the Humans take over, this could make the other species "under" Human rule to betray Shepard while he/she is on a mission, making his/her Service Record to show KIA, when he/she might be MIA.
Although, in the ending where you save the Council, but a bunch of people/aliens die, the Council could have sent Shepard on a mission where he/she went MIA, but the Council change his Service Record to KIA to make the losses "even".
Just pure speculation, don't take anything for granted.
Plus I'm like half asleep as I write this so it may not make much sense.
[Edited by yosup, 2/22/2009 7:04:28 PM]