Headscratchers / The Simpsons S7 E1 "Who Shot Mr. Burns? (Part Two)"

• Lisa's response when she sees the sundial:
  Lisa: So the DNA was right. It must have been... Oh, dad!

What exactly was she realising in this moment? The line and the way it's delivered make it sound like she's realising that her dad was, indeed, the shooter. But this doesn't line up with her defending her dad as innocent ("he wouldn't hurt a fly") at the hospital, or her sure assertion that Burns was trying to identify Maggie with the sundial ("W and S, or, from your point of view, M and S").

• I watched the clip in question, and it seems that she's realizing that Maggie is the shooter, especially with the emphasis on Burns's holster being empty and the camera angle changing to emphasize that from Burns's point of view, he saw the letters "M.S." Her reaction "Oh, dad!" thus appears to be her realizing that Homer is in danger of either being arrested for something he didn't do or being killed by the townspeople who are eager to claim the $50,000 reward that Smithers has offered for his capture.