Arye Gross will play the role of 'an intelligent and thoughtful scientist in his 50s who was once viewed as the most daring and innovative mind in his field' wich has been spoken few weeks ago.
Malcom Truss, the charachter's name, will meet the Fringe crew during the 5th episode of the Season Four.
So, my theory about his role as Robert Bischoff was wrong, but I don't give up hope to see the Walter's father again.