It took 36 days, but the truth is finally coming out. In a briefing for U.S congressional staff, oil behemoth BP admitted that it made a “fundamental mistake” in the hours leading up to last month’s fatal oil rig explosion. BP says that shortly before the explosion, which killed 11 workers, there were signs of a “very large abnormality” in its Gulf of Mexico well. But despite this, the company kept on drilling. BP also concedes that it was aware of possible contamination of the cement which closed the well off from natural gas, and there was an apparent failure to closely monitor signs of leaking, as well. (It was indeed erupting natural gas that destroyed the rig on April 20.) In the past, BP officials have dismissed what they now call “a very large abnormality” as a “not satisfactory” test result.