What is Confession note?

A confession note, typewritten and hand-signed, is found in Konrad’s room on the table beside his dead body. The note admits to killing Olesen and explains Konrad has committed suicide. K2 and everyone else except Patricia believe this closes the case – but as Patricia points out, Konrad has no typewriter. As K2 learns later as well, the spelling and grammar in the confession note are perfect, while Konrad’s other handwritten documents, including a memoir, are horribly written.