Reading through the emails and watching the video links, we are convinced it was Grey who murdered Mustard. Although the key logger was in German, and Brown had been acting strange, email 20 incriminates Plum. We also believe Scarlett knew about what was going on the whole time, given that Plum was talking to her about it. We just think Grey looks guilty.
In the image with the CD, there was a white bow tie which was last seen on Grey, we believe to be stolen from Brown. There was also the heart monitor which was not seen on Mustard as he entered the shower in video G but appears in the reflection.
We have kept track of the clues in a spread sheet with links to files on a team members computer.
Team Number One 