Two sources close to the situation told HornsDigest.com Vaughn's dismissal was the result of Vaughn's connection to NCAA violations that occurred while Vaughn was at Ole Miss.
Vaughn was the defensive backs coach and recruiting coordinator at Ole Miss from 2008 to 2011 under Houston Nutt.
The Associated Press has reported 13 of 28 NCAA violations committed by Ole Miss athletics involved the football program. According to reports, nine of the violations happened under current coach Hugh Freeze, but four of them occurred during the 2008-11 timeframe.
Here is UT's official release:
Longhorn Football assistant coach Chris Vaughn’s employment agreement with Texas will not be renewed
AUSTIN — Longhorn assistant football coach Chris Vaughn’s employment agreement with The University of Texas will not be renewed, Charlie Strong confirmed on Thursday.
“Chris did a tremendous job for us,” Strong said. “He’s a terrific football coach and a great person. However, circumstances have put us in a position that we are going to part ways.”
A veteran of 16 years in collegiate coaching, Vaughn spent the past two seasons coaching defensive backs at Texas.
He joined the staff in 2014, Charlie Strong’s first year with the Longhorns. That season, the Horns ranked 11th nationally in passing yards allowed (184.2 ypg), 15th in passing efficiency defense (110.04 rating) and 23rd in interceptions (15).
Senior CB Quandre Diggs became a sixth-round draft pick of the Detroit Lions and went on to play in 16 games, starting four. Last season, Vaughn helped a pair of starting true freshman corners earn honorable mention All-Big 12 honors in Davante Davis and Holton Hill.
Prior to Texas, Vaughn had coaching stops at Memphis, Ole Miss, Arkansas and Tulsa. A 1998 graduate of Murray State, he played linebacker for the Racers and earned All-Ohio Valley Conference honors as a senior.