A federal appeals court has ruled that a former BP engineer deserves a new trial on obstruction charges in connection to allegations that he deleted text messages detailing how much oil was spilling into the Gulf of Mexico in the wake of the 2010 Deepwater Horizon disaster.

Kurt Mix, 52, was convicted in 2013 of deleting more than 300 text messages, some of which revealed the actual amount of oil being spilled. Investigators recovered most of the text messages and discovered that BP was telling the public a massively deflated figure regarding how much oil was being released.

The spill, which lasted three months, released some 134 million gallons of oil and soiled 1,000 miles of Gulf of Mexico coastline, according to a lawsuit against the company that was settled Thursday for $18.7 billion, the largest US legal settlement over an environmental disaster.

No new trial has been scheduled, but Mix won a new trial Tuesday from the 5th US Circuit Court of Appeals, based in New Orleans. A three-judge panel concluded that misconduct by the jury forewoman prejudiced a deadlocked jury. "Even one juror's prejudice is sufficient to warrant a new trial," Justice Edith Clement wrote (PDF) for the three-judge appellate panel.

Further Reading Images from immediate aftermath of the Deepwater Horizon oil spill

The court found that the forewoman overheard in a courthouse elevator that other BP employees were also being prosecuted because of the spill. What she heard made her comfortable with voting guilty. The juror was accused of passing the information she overheard to the rest of the panel. Jurors returned two hours later with a guilty verdict.

"First, juror one was prejudiced by hearing that other BP employees were being prosecuted. Second, the rest of the jury was prejudiced by the foreperson's enigmatic statement that she heard outside information that gave her comfort in voting guilty," Clement ruled, adding that the forewoman "purposely exerted an extrinsic influence on the rest of the jury by telling them that she had overheard of something."

The head juror denied telling fellow panelists what she overheard.

Prosecutors urged the court to keep the verdict intact. They said the juror flap was "innocuous" and that US District Judge Stanwood Duval of New Orleans instructed the jury not to consider evidence learned outside the courtroom.

The appellate panel's decision upholds Duval's earlier mistrial ruling.

"We thought there was no question that the district judge made the right decision," said Douglas Hallward-Driemeier, Mix's attorney.

The decision came a month after David Rainey, who at the time of the spill was a BP vice president, was acquitted of lying to federal authorities in connection with their investigation of the disaster.

Eleven rig workers were killed when the DeepWater Horizon caught fire and eventually sank about 50 miles off the coast of Louisiana.

Rig supervisors Robert Kaluza and Donald Vidrine face 11 charges each of manslaughter over the spill. They have pleaded not guilty and face trial later this year.

Listing image by Sam Azgor