User blog comment:GrilledMeatling/Gravity Falls Theory: Who wrote the Books 3, 2, & 1/@comment-5774411-20140813024457

I believe it is old man mcgucket because there is a picture of a man looking slightly younger than mcgucket, but has six fingers, same hat, same band aid on beard. But old man mcgucket (present) has a bandage on the arm that possibly Bill cut his sixth finger...