The league fined the B.C. Lions all-star defensive lineman an unspecified amount Tuesday for multiple "throat slashing" gestures committed in the club's 19-18 win over the Edmonton Eskimos on Saturday night.
After the game, Mitchell defended his actions, saying he made a gesture in the form of a cross. But a television replay showed the defensive tackle making a throat-slashing gesture.
Earlier this season, Mitchell served a two-game suspension handed down by the CFL for violently hyper-extending the arm of Edmonton offensive lineman Simeon Rottier in the Eskimos' 27-14 win in Vancouver on July 20.
Mitchell was not penalized on the play but was still suspended by CFL commissioner Mark Cohon. Mitchell launched an unsuccessful appeal.
Saturday night's game was Mitchell's first against Edmonton since the incident with Rottier. Mitchell flattened the Eskimos guard on the first series Saturday night and walked away without incident after quarterback Steven Jyles was sacked.