NEW ORLEANS (AP) — Another BP executive was expected on the witness stand Thursday to face more questions from attorneys for the U.S. government, which is trying to prove the oil company is mostly to blame for a deadly explosion on the Deepwater Horizon rig that led to a massive oil spill.

Mark Bly led the company's internal probe of its 2010 blowout in the Gulf of Mexico, but said the investigation wasn't intended to look at the disaster through the "lens of responsibility."

"I think people should share information that could help learn about accidents," Bly said.

Attorneys for the U.S. government and lawyers for Gulf Coast residents and businesses have accused BP of putting profits ahead of safety on a project that was over budget and behind schedule. BP has said drilling in the Gulf is a team effort and its partners should share in the responsibility for the disaster. The trial is designed to assess the fault of each company involved, and billions of dollars are at stake.

On Wednesday, a well design expert and geophysicist who worked for Conoco and Exxon, said BP withheld critical information from oil and gas regulators and continued drilling despite clear signs of trouble before the blowout of the Macondo well.

Alan Huffman, the federal government's expert, said BP continued drilling in dangerous deep water conditions without keeping the Minerals Management Service fully informed about changes in its plans.

Huffman said his review of internal BP documents and MMS records showed the London-based oil giant engaged in a "consistent pattern of misreporting" to the federal agency and gave it a "very false impression" of what was happening on the drilling project.

"And this happened on multiple occasions ... not just on one or two," said Huffman, the second expert witness at a trial that started Monday and, barring a settlement, could last several months.

During his cross-examination, Huffman acknowledged he had never been asked to make a similar comparison of regulatory records before the Justice Department hired him.

"Are you in the business of determining whether or not regulations have been violated?" BP attorney Matt Regan asked.

"That is not my normal practice of work, no," Huffman said.

Regan also questioned why Huffman didn't thoroughly examine the actions of Transocean rig workers or compare BP's conduct to that of other offshore operators.

Huffman said BP did seek permission from MMS to change its drilling plans on some occasions. Other times, he testified, the company's engineers forged ahead with drilling the well when it was in a potentially unsafe condition without informing the agency.

"And that is not what a prudent operator does," he said.

Huffman said it was "unwise" for BP to continue drilling after rig workers detected a "kick," or unexpected increase of pressure in the well, the month before the April 20, 2010, blowout.

"This drilling ahead in this environment was not only unsafe, it violates every standard I can think of in how wells are drilled in the deep water and elsewhere in our industry," he said. "It is truly egregious to drill that extra hundred feet knowing that you could potentially lose the well in the process."

Former BP chief executive Tony Hayward also made a cameo appearance Wednesday, but he didn't attend in person. Instead, he showed up just briefly on a videotape in what may be his only appearance in the courtroom.

Hayward, who infamously said "I'd like my life back" at the height of the spill, isn't expected to take the witness stand in the high-stakes trial because he didn't have direct knowledge of the drilling operations on the Deepwater Horizon.

Still, attorneys for the U.S. government and Gulf Coast residents and businesses showed a 20-minute snippet of his deposition, projecting the video on a large white screen in the courtroom.

"I believe that the role of leaders is very important in shaping the culture of an organization," Hayward said in the videotape.

Rig owner Transocean Ltd. and cement contractor Halliburton also are defendants and their lawyers have tried to minimize their roles in the disaster.