Thierens said he didn't know that BP had to submit a regional oil spill response plan to federal regulators from an agency that was known as the Minerals Management Service at the time of the April 20, 2010, blowout.
"So BP submitted this to the MMS for the Gulf of Mexico without clearing it through its Wells Director?" a lawyer from Alabama Attorney General Luther Strange's office asked.
"Yeah, I don't recall having seen this," said Thierens, who added that he didn't look at the plan while working on the spill response, either.
Thierens, who has since left BP, had described his job responsibilities as including "accountability for all aspects of MMS regulatory requirements. But he could only recall having direct contact with MMS once during his three-year tenure as wells director and couldn't recall if he ever looked at any of the regulations governing Gulf drilling.
Alan Huffman, a well design expert who testified at the trial earlier this week as a witness for the federal government, said BP continued drilling in dangerous deep water conditions without keeping the Minerals Management Service fully informed.
Huffman said his review of internal BP documents and MMS records showed the 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.