A federal jury deliberated for more than nine hours since hearing closing arguments Monday before reaching a verdict on Kurt Mix's case. The count of obstruction of justice carries a maximum sentence of 20 years in prison and a $250,000 fine.
Mix will be released on his present bond, and sentencing is scheduled for March 26.
Mix hugged his friends and family members in the courtroom before leaving hurriedly, getting on an elevator and leaving the courthouse.
"I'm only going to speak through counsel," he said to Associated Press questions.
Prosecutors argued that Mix, 52, of Katy, Texas, was trying to destroy evidence when he deleted hundreds of text messages to and from a supervisor and a BP contractor. Mix's indictment also accused him of deleting two voicemails from the same two people.
Mix's lawyers said their client didn't hide anything. He preserved other records containing the same information contained in the deleted messages, they told jurors.
Mix, who didn't testify at his two-week trial, was one of four current or former BP employees charged with crimes related to the spill. His case was the first to be tried.
The April 20, 2010, blowout of BP PLC's Macondo well triggered an explosion that killed 11 workers on the Deepwater Horizon drilling rig and spawned the nation's worst offshore oil spill. Millions of gallons of oil spewed into the Gulf while the company scrambled for weeks to seal the well.
Mix was on a team of experts who worked on BP's unsuccessful attempt to stop the gusher using a technique called "top kill." He had access to internal data about how much oil was flowing from the blown-out well.
On May 26, 2010, the day that top kill began, Mix estimated in a text to a supervisor that more than 630,000 gallons (2.4 million liters) of oil per day were spilling - three times BP's public estimate of 210,000 gallons daily and a rate far greater than what top kill could handle.
That text was in a string of messages that Mix exchanged with his supervisor, Jonathan Sprague, before deleting it in October 2010. Investigators couldn't recover 17 of the messages in the string.
In August 2011, Mix also deleted a string of text messages that he exchanged with BP contractor Wilson Arabie. Several weeks earlier, federal authorities issued a subpoena to BP for copies of Mix's correspondence. The same count that charges Mix with intentionally deleting those messages also says Mix deleted a voicemail from Arabie and a voicemail from Sprague.