1. When the dead body of the lawyer was discovered in his room, the doctor should have immediately been called. Not only does Matt not call on the doctor (who should at least be a witness) but the doctor himself doesn't show any concern or go upstairs to see the body.
2. When the killer comes through the secret bookcase entrance to attack, the first thing I would do is go out the door, if it was not locked. This guy doesn't even try.
"Cum Grano Salis"