Rep. Henry Waxman says that his committee's investigation into the Gulf oil spill reveals that a key safety device, the blowout preventer, had a leak in a crucial hydraulic system.

The California Democrat said in a hearing Wednesday that the investigation also discovered that the well had failed a negative pressure test just hours before the April 20 explosion.

He cited BP documents received by the Energy and Commerce Committee that showed there was a breach in the well integrity that allowed methane gas and possibly other hydrocarbons to enter the well.