NEW ORLEANS (AP) -- Defense attorneys for a former BP engineer convicted of trying to obstruct a federal investigation of the company's 2010 Gulf oil spill claimed Thursday that jurors engaged in misconduct that warrants a new trial.
Kurt Mix's attorneys asked U.S. District Judge Stanwood Duval Jr. to throw out the jury's Dec. 18 verdict convicting Mix of one count of obstruction of justice for deleting text messages to and from a BP supervisor.
Mix's lawyers said they interviewed jurors after the verdict and learned that one juror told the others during their deliberations about overhearing a conversation in a courthouse elevator that made that juror feel more comfortable about convicting Mix.
Their court filing doesn't specify the substance or possible source of the information that "Juror A" allegedly overheard in the elevator, but it says other jurors urged the person not to reveal any of those details.
"By doing so, Juror A directly injected into the jury room the idea that there existed powerful, additional proof of Mr. Mix's guilt that had not formally been allowed into evidence but that Juror A had come to obtain," defense attorneys wrote. "It is difficult to imagine a more prejudicial scenario."
Mix's attorneys also said some jurors, during conversations outside the deliberation room, apparently engaged in "horse trading" that would ensure a split verdict. Jurors acquitted Mix of a second count of obstruction of justice for deleting a string of text messages with a BP contractor.
The defense lawyers urged Duval to determine the extent of any misconduct.
"Given the circumstances of this case, the Government will have an extremely difficult time rebutting the presumption of prejudice," they wrote. "The evidence against Mr. Mix was, to put it mildly, not strong."
A Justice Department spokesman didn't immediately respond to an email seeking comment.
Mix, 52, of Katy, Texas, faces a maximum sentence of 20 years in prison and a $250,000 fine. His sentencing is set for March 26.
During his tenure at BP, Mix received 10 separate notices from the company that he was obligated to preserve all of his spill-related records. But the jury concluded that he broke the law in October 2010 when he deleted a string of text messages to and from his supervisor, Jonathan Sprague.
Mix worked on a team of experts who tried in vain to stop BP's spill using a technique called a "top kill." He had access to internal data about how much oil was flowing from the blown-out well.
On May 26, 2010, the day that top kill began, Mix estimated in a text to Sprague that more than 630,000 gallons of oil per day were spilling — three times BP's public estimate of 210,000 gallons daily and a rate far greater than what top kill could handle.
Mix was the first of four current or former BP employees charged with spill-related crimes and the first of them to be tried.