The US Congress has called oil giant BP and its drilling partners to account for a "cascade of failures" behind the spreading spill in the Gulf of Mexico.
Senators homed in on a crucial chain of events at the deep-sea wellhead just before an explosion consumed the rig and set off the catastrophic rupture.
In back-to-back Senate inquiries, executives of the three companies at the heart of the massive spill were chastised because of attempts to shift the blame to each other.
They were asked to explain why better preparations had not been made to head off the accident.
"Let me be really clear," Lamar McKay, chairman of BP America, told the hearing. "Liability, blame, fault - put it over here.
"Our obligation is to deal with the spill, clean it up and make sure the impacts of that spill are compensated, and we're going to do that."
By "over here", Mr McKay meant the witness table at which BP, Transocean and Halliburton executives sat shoulder to shoulder. And despite his acknowledgement of responsibility, each company defended its own operations and raised questions about its partners in the project gone awry.
Politicians compared the calamity to some of history's most notorious mishaps from sea to space in the first congressional inquiry into the April 20 explosion and so-far unstoppable spill.
Democratic senator Jeff Bingaman, chairman of the Energy and Natural Resources Committee, said: "If this is like other catastrophic failures of technological systems in modern history, whether it was the sinking of the Titanic, Three Mile Island, or the loss of the Challenger, we will likely discover that there was a cascade of failures and technical and human and regulatory errors."
Senators sought assurances that BP would pay what could amount to billions of dollars in economic and environmental damages. Mr McKay repeatedly said his company would pay for clean-up costs and all "legitimate" claims for damages, and not try to limit itself to an existing government limit of £50 million on such damages.