In your journal there are 3 pages allocated to Hamilton's murder.
You need to have no red question marks before you reach the sanctuary because you can't turn back once you trigger the end sequence.
The only one that is supposed to be not filled by the time you reach this point is on the bottom of the third page, this one isn't missable.
Ask if you are missing any and I'm sure someone will help out.
I missed the bottom of the right page, it's in the bin near the garage that the wolves are hanging around.
I missed the middle of the left page, it's painted on the side of Lamothe's house.http://imgur.com/a/Tvzix