If you keep him spawned, by looking at him or by being inside his activation area, he'll always remain alive, and will keep going back and forth.
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This is grunt mechanics but should apply almost the same as brute too when we talk about position:
http://www.youtube.com/watch?v=xWPU6frXmUY
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Also, Add a lot of pathnodes around the map! pathnodes are the position that the monster can reach to navigate around, if there are no nodes on every corridor the monster will just run towards the walls or just stay idle!
Watch Amnesia's default maps (like the prisons) to understand how to put the pathnodes