Private military contractors under scrutiny

Blackwater USA
Erik Prince, chairman of the Prince Group, LLC and Blackwater USA, holds up a picture showing the affect of a car bomb while testifying during a House Oversight and Government Reform Committee hearing on Capitol Hill Oct. 2, 2007 in Washington.
Photo by Mark Wilson/Getty Images

Blackwater Worldwide is perhaps one of the higher profile private military contractors in Iraq, but they're not the only one.

Blackwater's involvement in the killing of 17 civilians in Iraq and the subsequent investigations highlight the problem of how to hold "soldiers for hire" accountable when things go wrong.