NEW ORLEANS (AP) — Federal prosecutors brought the first criminal charges Tuesday in the Gulf oil spill, accusing a former BP engineer of deleting more than 300 text messages that indicated the blown-out well was spewing far more crude than the company was telling the public at the time.
Two years and four days after the drilling-rig explosion that set off the worst offshore oil spill in U.S. history, Kurt Mix, 50, of Katy, Texas, was arrested and charged with two counts of obstruction of justice for allegedly destroying evidence.
His attorney, Joan McPhee, issued a statement Tuesday evening describing the charges as misguided and that she is confident Mix will be exonerated.
‘‘The government says he intentionally deleted text messages from his phone, but the content of those messages still resides in thousands of emails, text messages and other documents that he saved,’’ she said. ‘‘Indeed, the emails that Kurt preserved include the very ones highlighted by the government.’’
The U.S. Justice Department made it clear that the investigation is still going on and suggested that more people could be arrested. In a statement, Attorney General Eric Holder said prosecutors ‘‘will hold accountable those who violated the law in connection with the largest environmental disaster in U.S. history.’’
Federal investigators have been looking into the causes of the blowout and the actions of managers, engineers and rig workers at BP and its subcontractors Halliburton and Transocean in the days and hours before the April 20, 2010, explosion.
But the case against Mix focuses only on the aftermath of the blast, when BP scrambled for weeks to plug the leak. Even then, the charges are not really about the disaster itself, but about an alleged attempt to thwart the investigation into it.
In court papers, the FBI said one of the areas under investigation is whether the oil company intentionally lowballed the amount of crude spewing from the well.
In outlining the charges, the government suggested Mix knew the rate of flow from the busted well was much greater than the company publicly acknowledged.
Prosecutors also said BP gave the public an optimistic account of its May 2010 efforts to plug the well via a technique called a ‘‘top kill,’’ even though the company’s internal data and some of the text messages showed the operation was likely to fail.
An accurate flow-rate estimate is necessary to determine how much in penalties BP and its subcontractors could face under the Clean Water Act. In court papers, prosecutors appeared to suggest the company was also worried about the effect of the disaster on its stock price.
The charges came a day before a federal judge was to consider granting preliminary approval of a $7.8 billion civil settlement between BP and a committee of plaintiffs.
In a statement, BP said it is cooperating with the Justice Department and added: ‘‘BP had clear policies requiring preservation of evidence in this case and has undertaken substantial and ongoing efforts to preserve evidence.’’
The FBI said in court papers that Mix had been repeatedly notified by BP that instant messages and text messages needed to be preserved.
Mix, who resigned from BP in January, appeared on Tuesday afternoon before a judge in Houston, shackled at his hands and feet, and was released on $100,000 bail. His attorney had no comment afterward. If convicted, Mix could get up to 20 years in prison and a $250,000 fine on each count.
The engineer deleted more than 200 messages sent to a BP supervisor from his iPhone containing information about how much oil was spilling out, then erased 100 more messages to a contractor the following year, prosecutors said. Some of the messages were later recovered via forensic computer techniques.
Many of the messages had to do with an effort to plug up the well with heavy mud injected under high pressure.
In public statements, the company professed optimism that the top kill would work, giving it a 60 to 70 percent chance of success.
On the day the top kill began, Mix estimated in a text to his supervisor that more than 15,000 barrels of oil per day were spilling — three times BP’s public estimate of 5,000 barrels and an amount much greater than what BP said the top kill could probably handle.
At the end of the first day, Mix texted his supervisor: ‘‘Too much flow rate — over 15,000 and too large an orifice.’’ Despite Mix’s findings, BP continued to make public statements that the top kill was proceeding according to plan, prosecutors said. On May 29, the top kill was halted and BP announced its failure.
The company’s stock dropped 15 percent on the next trading day, the government said.
David Uhlmann, a University of Michigan law professor who was chief of the Justice Department’s environmental crimes section, said the charges are probably ‘‘just the first of what will be multiple criminal charges.’’
‘‘It could be the sign that the government believes there was a more far-reaching cover-up about the size of the spill,’’ he said.
BP stock closed at $41.91 Tuesday, a drop of just 4 cents. Analysts said investors evidently recognized the charges involved just one, low-ranking employee and saw no hint yet of any kind of larger cover-up on BP’s part.
The explosion aboard the Deepwater Horizon drilling rig killed 11 workers. More than 200 million gallons of crude oil leaked from the well off the Louisiana coast before it was capped.
Under the Clean Water Act, polluters can be fined $1,100 to $4,300 per barrel of spilled oil, with the higher amount imposed if the government can show the disaster was caused by gross negligence.
Al Sunseri, whose family-owned oyster business was damaged by the spill, said there was little real news in the arrest of Mix. ‘‘I personally believe it’s so involved that we could never really understand the magnitude of the bad players involved,’’ he said.
Billy Nungesser, president of hard-hit Plaquemines Parish who has long accused BP of misleading the public about the spill, said: ‘‘We’re just glad that the truth, and all the truth, will come out. Where crimes were committed, BP needs to pay the price.’’
Associated Press reporters Kevin McGill in New Orleans and Ramit Masti-Plushnick in Houston contributed to this story.