Another good book on subject.
"The Sociopath Next Door" is a great book for understanding true psychopathy (not the limited definition that this study uses), another is "Snakes in Suits" by Paul Babiak, Ph.D., and Robert D. Hare, Ph.D. Whereas '..Next Door' deals with ones found in our regular lives, '..Suits' deals with sociopaths in the workplace, both as employees as well as supervisors. It helps in identifying them and how to deal with them (the best way is to avoid them entirely but oftentimes that is not possible.