The Deepwater Horizon joint investigation concluded the fourth day of the fourth session of hearings August 26 into the circumstances surrounding the explosion, fire, pollution and sinking of the Mobile Offshore Drilling Unit Deepwater Horizon, with multiple loss of life in the Gulf of Mexico on April 20, 2010. The joint investigation has the powers of both convening agencies, the United States Coast Guard (USCG) and the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEM), and is co-chaired and staffed by representatives of both agencies.