(Melissa R. Nelson ~ Associated Press)
The report concluded that BP violated federal regulations, ignored crucial warnings, was inattentive to safety and made bad decisions during the cementing of the well a mile beneath the Gulf of Mexico.
Eleven rig workers were killed in the April 2010 explosion, and some 200 million gallons of crude spewed from the bottom of the sea.
The investigation was conducted by a team from the two main agencies responsible for drilling and safety in federal waters: the Coast Guard and the Bureau of Ocean Energy Management Regulation and Enforcement.
In the report, other companies shared some of the blame. Rig owner Transocean was accused of being deficient in preventing or limiting the disaster, in part by bypassing alarms and automatic shutdown systems. Halliburton, the contractor responsible for mixing and testing the cement, was faulted as well.
(Melissa R. Nelson ~ Associated Press)
The report identifies many of the same causes and faulty decisions found by previous investigations, including those conducted by a presidential commission, congressional committees and the companies themselves. But some of those earlier investigations spread the blame more evenly.
The new report also marks the first time an investigative body looking into the spill has identified specific violations of federal regulations by BP and its contractors.
The findings will be used to shape reforms in offshore drilling safety and regulation. They will also be used by lawyers for victims involved in court battles over the oil spill, and by government agencies considering charges and penalties.
"It is only a question of time before BP -- along with Transocean and Halliburton -- will face criminal charges for their roles in the Gulf oil spill," said David Uhlmann, a University of Michigan law professor who formerly led the Justice Department's environmental crimes section.
The Justice Department hasn't commented on where its probe stands.
Congressional leaders immediately scheduled hearings to discuss the findings,
BP responded to the report by saying it is time for "other parties to acknowledge their roles in the accident and make changes to help prevent similar accidents in the future." Transocean said it takes exception to any criticism of its drill crew. Halliburton did not comment.
In the report, the primary cause of the disaster was identified -- again -- as the failure of the cement seal in the well. While it was Halliburton's job to mix and test the cement, BP had the final word and made a series of decisions that saved money but increased risk and may have contributed to the cement's failure, the panel said.
The report said BP, and in some cases its contractors, violated seven federal regulations at the time of the disaster.
The violations include failure to take necessary precautions to keep the well under control at all times, and failure to securely cement the well and maintain the blowout preventer. Cement is used as a barrier in wells to keep the highly pressurized oil and gas bottled up.
This report is likely to carry more weight in Congress than the other investigations. Republican lawmakers had said they were unwilling to adopt reforms until the federal investigation was complete.
Since the disaster, the Obama administration has reorganized the offshore drilling agency and boosted safety regulations. But Congress has yet to pass a single piece of legislation to address safety gaps highlighted by the disaster.
The panel recommended further changes to offshore drilling practices, including requiring at least two barriers in a well -- one mechanical, one cement. BP's well had a single barrier, the cement. The last line of defense, the blowout preventer, failed because a kink in the well pipe prevented the device from pinching the well shut, the panel found.
In the report's 57 findings, only one person -- BP engineer Mark Hafle -- is mentioned by name. It said Hafle failed to investigate or resolve anomalies detected during the cementing and did not run a test that evaluates the quality of the cement job. Hafle still works for BP.
Hafle refused to testify before the federal panel in the summer of 2010, citing his constitutional right against self-incrimination.
"Will this be the investigation that goes past corporate plea deals and fines to handcuffs and jail time? It's an open question," said Kendall Coffey, former U.S. attorney in Miami. "I think this Justice Department is going to try hard to make cases against individuals and seek prison time if that can be justified."
Associated Press Writer Curt Anderson contributed to this report from Miami.
Weber reported from Atlanta. Follow him at http://www.facebook.com/HarryRWeberAP
Cappiello reported from Washington. Follow her at http://twitter.com/dinacappiello