US authorities made their first arrest Tuesday in the 2010 Deepwater Horizon disaster, charging an ex-BP engineer with destroying evidence tied to the country's largest-ever environmental disaster.

The Justice Department said it had charged drilling engineer Kurt Mix, 50, with two criminal counts of obstruction of justice for trying to destroy hundreds of text messages on his iPhone that related to the incident

The messages, some of which investigators recovered, showed BP knew that the leak was more than three times larger than its official estimates and that its "Top Kill" effort to plug the well at the end of May 2010 was failing.

Mix, of Katy, Texas, is the first person to be charged in the April 2 0, 2010, disaster that killed 11 men and sent millions of barrels of oil leaking into the Gulf of Mexico, killing sealife and coating shores popular with tourists.

The messages Mix allegedly attempted to wipe from his iPhone came from the weeks after the Macondo well blowout, when BP sought to halt the subsea leak.

The charges say Mix was part of BP staff trying to estimate the amount of oil flowing from the well for the Top Kill effort aimed at halting it.

According to the charges, he sent hundreds of "real time" messages to a BP supervisor on the flow of the well and progress of the operation.

BP , based in Britain, had reported at the time that the well was leaking about 5,000 barrels a day of crude oil.

The messages allegedly give a different picture.

"Too much flowrate -- over 15,000," said one message Mix sent on May 26, the first day of the operation.

Even before the operation commenced, the Justice Department said, "Mix and other engineers had concluded internally that Top Kill was unlikely to succeed if the flow rate was greater than 15,000 barrels of oil per day."

The effort in fact did fail and the well flowed for 10 weeks more until a new effort plugged it on August 4, after 4.9 million barrels of oil had polluted the Gulf of Mexico waters.

US authorities said Mix had been under instructions from BP to retain all communications.

However, it said, as investigations were launched into the disaster, on two instances in mid-August 2010 and then again in October, he deleted strings of text messages relating to the Top Kill operation.

"By the time Mix deleted those texts, he had received numerous legal hold notices requiring him to preserve such data and had been communicating with a criminal defense lawyer in connection with the pending grand jury investigation of the Deepwater Horizon disaster," the department said.

In a statement BP said it was coorperating with the investigation and that the company "had clear policies requiring preservation of evidence in this case."

Mix faces up to 20 years in prison and a fine of up to $250,000 on each count if convicted.

"The Deepwater Horizon Task Force is continuing its investigation into the explosion and will hold accountable those who violated the law in connection with the largest environmental disaster in US history," US Attorney General Eric Holder said in a statement.