How do you and I know the killer is not in here?!

Alan: [About G.D. Thibodeaux] I’ll tell you what I’m gonna go. I’m gonna go down there and talk to him.
Lindsey: No, no, no, no!
Alan: I’ve got to. I’ve got to! You sit here where you’re fine.
Lindsey: That is not fine. How do you and I know the killer is not in here?!
Alan: Because you’re around too many people.
Lindsey: No, no, no, no. Please, don’t!
Alan: I’m gonna go talk to him.
Lindsey: No, that is not a good idea!
Alan: I think it’s … where’s Drew? Hey Drew!
Lindsey: No. No! He could be the killer!