Kurt Mix, a former engineer at BP, has been charged by the FBI with obstruction of justice, after allegedly deleting data and text messages around the 2010 Gulf of Mexico oil spill from his iPhone.

Mix, a drilling and completions project engineer working at BP to stem the leak, allegedly deleted more than 200 text messages with a supervisor, according to a complaint unsealed yesterday in an Eastern District of Louisiana court. He had been told by BP to retain all data, it is alleged.

Mix was allegedly texting his supervisor, on his iPhone, with sensitive information on BP’s efforts to stem the well. Some of the texts were recovered forensically.

He is accused of deliberately deleting the text messages, around 4 October 2010, when he learned that his electronic files were due to be collected by BP’s lawyers.

In one text from 26 May 2010, at the end of the first day of BP’s ‘Top Kill’ effort to plug the leak, Mix stated: “Too much flowrate—over 15,000.” Before Top Kill commenced, 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 (BOPD).

Additionally, BP’s public estimate of the flow rate was 5,000 BOPD at the time, three times lower than the minimum flow rate indicated in Mix’s text.

Around 19 August 2011, Mix learned that his iPhone was due to be imaged by a vendor working for BP’s outside counsel. He then allegedly deleted a text string of over 100 messages to a contractor. The FBI alleges that he had received “numerous notices” ordering him to preserve the data, pending a grand jury investigation.

The accusations represent the first criminal charges to result from the Deepwater Horizon Task Force investigation.

If found guilty, Mix faces up to 20 years in prison, and a fine of up to $250,000 for each of the two counts of obstruction of justice. It remains unclear how he will plea.

Attorney General Eric Holder said: “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.”