Originally Posted by Helbore:
“I thought it would be his daughter. She lost her husband and son to the Silurians. Now her dad may be dying from their venom. She was also the one to bring all those weapons (and didn't seem like she put them away when the Doctor told her to, either)
She has the best motive and opportunity to carry out the killing.”
Yeah, she's got the look in her eyes, the motive and the tools.
The dad has also been seen to be aggressive and territorial, and now he's been badly, possibly fatally injured by them. So he also has a motive.
Therefore, we can be sure it's not going to be either of them.
My money's on Rory. Seriously. They've got Amy, and they're threatening to hurt her.