WSJ reports:

Oil giant BP PLC told congressional investigators that a decision to continue work on an oil well in the Gulf of Mexico after a test warned that something was wrong may have been a “fundamental mistake,” according to a memo released by two lawmakers Tuesday.
The document describes a wide array of mistakes in the fateful final hours aboard the Deepwater Horizon — but the main revelation is that BP now says there was a clear warning sign of a “very large abnormality” in the well, but work proceeded anyway.
The rig exploded about two hours later.
The congressional memo outlines what the lawmakers say was a briefing for congressional staff by BP officials early Tuesday. Company representatives provided a preliminary report on their internal investigation of the April 20 disaster, which killed 11 workers and continues to spill thousands of barrels of oil daily into the Gulf of Mexico.

The rest here.