I need some more help

I thought I'd never have to do one of these things, but I was wrong.  I remember seeing this horror film a long time ago and just can't remember the name for the life of me.

This is what I remember.  It took place in space (I think).  Some kind of creature wiped out this entire base.  They decided to take space prisoners and send them in with guns to clear out what was inside.  So in they go, yada yada yada.  It starts killing off the prisoners one by one.  You never actually get to see the killer, its a POV type deal.  Until the very end, that is.  It turns out that one of the space prisoners was the creature the whole time.  The last scene is somewhat like the new Hills 2 photo, with the two survivors helping the third survivor, in between them, walk out of the base.  It's confusing, I know.  Any help would be appreciated.  I've been trying to remember the name of this film for a long time.

And trust me, it's not The Thing.