I played the previous two Arkham games and I know there was a way to jump on temporarily downed enemies (the ones with stars floating around their heads) and finish them off so they wouldn't get back up. I just started Arkham Origins and can't figure out how to do this, though, and looking in the control options didn't show me any particular button that I need to press.
I'm pretty sure I always had that ability from the start in the previous games. Have I just not unlocked it yet, or am I just not finding the right button combo to press?