The Elder Scrolls IV: Shivering IslesMore guides, cheats and FAQS
In a cave called Corpserot Prison at the very beginning of the cave, you will find the evidence chest. It is in both Mania and Dementia. On your map, it is called Corpserot Passage.
A Death Note:
Near Dunroot Burrow on top of a hill are a couple slabs of stone. On those slabs is a dead person, with a Potion of Nighteye nearby, some skeletons, and a note. The note is called Death Decree. It says that a man named "Robert Wisnewski", a member of the Bethesda staff, was sentenced to death. The reason for his death was for trying to grow a beard.