Guy had evidence to clear himself all along but didn't use it
Maybe I am missing something, but it seemed that Guy had evidence to prove his version of the events and thus his innocence with Bruno's map. I kept thinking that there would be a plot twist with the map and that it would be inaccurate and Guy would bring it to the police only to find out the map was fake and it would cast more suspicion on himself somehow.
I was so surprised to see the map was accurate but Guy didn't use it to clear himself. It seemed so obvious to me including the note "my father's room" on the map would clearly point to Bruno if it turned out to be accurate.
How else would Guy be able to create an accurate map of the inside of the Antony house unless he got it from Bruno? I
think using the proof that Bruno was the real killer because he had his lighter was so much weaker than the map. There were a myriad of reasons for Bruno to have his lighter. Guy could have planted it in his pocket during the fight, Bruno could have found it and was intending to return it since they had been at a few social events recently...but the map would be definitive proof of the criss cross scheme that Bruno proposed.