The oil giant BP has admitted it proceeded with work on the underwater oil well in the Gulf of Mexico shortly before last month’s explosion despite warning signs of a major problem. Dogged by delays, BP faces a pivotal day today as it attempts a so-called “top kill” maneuver to choke off the gushing oil by pumping heavy drilling mud and cement into the mile-deep well. The procedure risks making the leak worse. A weak spot in the device could blow under the pressure, causing a brand new leak. We speak to Abrahm Lustgarten, a reporter for the investigative news website ProPublica who has reported on BP for many years.