Gray accepted a position as the defensive coordinator for the Tennessee Titans, the team announced on Saturday.
"I also want to thank Coach Brown and University of Texas," Gray said in a release. "I know the timing of this isn’t ideal, but this was something that I couldn’t turn down."
Gray's vacancy means Brown will launch a search for his seventh coaching hire of the offseason. Gray came to Texas on January 17 after coaching defensive backs for the Seattle Seahawks in 2010.