Limit Liability for actions performed by your Property Manager

saw this article from a weeks ago (http://news.yahoo.com/s/ap/20110502/ap_on_re_us/us_monoxide_deaths_landlord_charged) where the result of a landlord’s good intentioned actions resulted in the deaths of his tenants.

Since I use a property manager, I was just curious on what you all have done to limit your liability for actions done by your property manager. Did you add certain provisions to your property management contract ? any other steps ?