UC Berkeley professor Dr. Robert Bea is an expert in off-shore oil rig accidents, and he was asked by the White House last week to analyze the BP disaster in the Gulf. As 60 Minutes reports, Dr. Bea also investigated the Challenger disaster, and the Hurricane Katrina disaster -- after which his voice never fully recovered.

Below, Dr. Bea discusses the evidence he has with which to analyze the cause of the spill via eyewitness testimony from rig crewmember Mike Williams.