LOS ANGELES — Southern California athletic director Mike Garrett told ESPN that former Trojans guard O.J. Mayo refused to cooperate in a university investigation.

The school was looking into allegations that Mayo accepted improper gifts and benefits while he played for the school during the 2007-08 season.

Garrett says Mayo has not participated. Mayo now plays for the Memphis Grizzlies.

USC announced last week that it had imposed sanctions on the basketball team for recruiting violations involving Mayo, including a ban on postseason play this season.

USC will also vacate its wins during the 2007-08 season.

USC’s self-imposed punishment comes at the same time the school faces allegations that current football player Joe McKnight and former Heisman Trophy winner Reggie Bush accepted improper benefits.