A drilling engineer for British oil giant BP was cleared of obstructing justice during 2010 Gulf of Mexico oil spill, his lawyers said Friday.

Kurt Mix, who worked on efforts to stop oil from gushing out of BP's runaway well, was found guilty in 2013 of obstruction charges because he deleted text messages sent to and received from his manager.

Prosecutors dropped the obstruction charges against Nix Friday after he agreed to plead guilty to a single misdemeanor charge.

He was one of a handful of BP employees who faced criminal charges in the deadly April 20, 2010 explosion on the Deepwater Horizon rig.

The blast killed 11 workers and it took 87 days to plug the well that was 5,000 feet (1,500 meters) below sea level and 80 kilometers (50 miles) offshore from New Orleans.

The disaster blackened beaches in five states with raw oil and crippled the region's tourism and fishing industries in a tragedy that riveted the United States.

Nix's lawyers said all the text messages he deleted were personal in nature and noted that his manager was also a close personal friend.

A transcript they provided showed a series of messages largely about lunch plans, family matters and what appear to be rather banal chats about work issues.

"This is a case that never should have been brought, against a man whose tireless efforts in the Deepwater Horizon spill should have been acknowledged and appreciated, not prosecuted," defense attorney Joan McPhee said in a statement.

Four other people have been criminally charged in the spill, according to the New Orleans Times Picayune.

Former BP vice president David Rainey, who coordinated the company's response, was indicted on obstruction charges in 2011 for allegedly lying to Congress about how much oil was gushing out of the well. He was acquitted in June.

BP's site leaders aboard the drilling rig, relatively low-level employees Donald Vidrine and Robert Kaluza, face involuntary manslaughter charges for allegedly ignoring pressure tests that showed dangerous conditions were developing. They are set to face trial in February.

Halliburton manager Anthony Badalamenti received probation in January after pleading guilty to destroying evidence by deleting computer records related to the spill.

BP's total pre-tax costs for the spill were $55 billion, according to third quarter results reported last week.