Top executives of BP and two of its partners in the exploded Deepwater Horizon oil rig pointed fingers at one another before a Senate panel this week, in the first of several hearings before Congress. (Watch a CBS report about the CEOs passing the blame.) Here's a brief look at the accusations, and who's making them, as BP, TransOcean, and Halliburton publicly juggle liability for the deadly and environmentally disastrous oil spill in the Gulf of Mexico:

BP AMERICA Lamar McKay, chairman
Responsible for: Overall project operation; BP owned the oil well
The charge: BP's partners say it cut corners on safety. According to two rig workers and the other two companies, BP ordered gas-blocking heavy drilling fluid (or "mud") removed from the well before a cement plug was in place, an apparent diversion from normal protocol. An escaped methane gas bubble is believed to have caused the explosion.
The response: McKay blamed TransOcean for installing an apparently defective blowout preventer. That 450-ton valve is supposed to cap the well in such emergency situations.

Responsible for: Crucial well safety equipment; TransOcean owned Deepwater Horizon drilling rig
The charge: As "owner and operator" of the rig, TransOcean had "responsibility for the safety of drilling operations," McKay testified. The company's malfunctioning blowout preventer "was to be the fail-safe in case of an accident," he said.
The response: TransOcean said the blowout preventer tested just fine a week before the explosion. Newman said ultimate responsibility for anything that happens on the rig belongs to BP, but he also blamed Halliburton for the "sudden, catastrophic failure of the cement, the casing, or both," that was supposed to have sealed the well.

HALLIBURTON Tim Probert, president for global business
Responsible for: Sealing the well with cement
The charge: Halliburton workers didn't properly and completely plug the well, accusers say. If they had, the gas wouldn't have escaped and caused the explosion.
The response: Pobert blamed BP, TransOcean, and also federal regulators. Halliburton simply followed BP's instructions and federal regulations, he said, and if the blowout preventer had "functioned as expected, this catastrophe may well not have occurred."

Sources: CNN, Yahoo News, LA Times, Salon, Bloomberg