Yes, it's amazing what assumptions can be made when presuming guilt before innocence, eh?
This is a message board, not a court of law. And nobody is presuming guilt, we are just not presuming innocence either.
Investigators are not there to presume innocence; that is the role of the court. The investigator is there to ascertain facts. This email is very careful to avoid giving out much in the way of hard fact, and the emailer's tactics seem to be very carefully aimed at avoiding prison time as opposed to actually protecting his family.
Flight to avoid investigation has always been viewed as a sign of guilt from the first days of the Republic. It is a case of actions speaking louder than words.