"I stepped down today from my coaching duties at USC," Garza said in a statement. "I have some personal issues unrelated to USC that I need to address. I wish the Trojans the best and I am sorry I won't be with them in what I know will be a very successful season."
A school spokesman said USC head coach Lane Kiffin would not comment today on Garza's departure. While Garza was not at practice Thursday morning, Kiffin gave no indication Garza was about to leave the program.
Players were informed by text message at noon.
Garza, 41, was entering his second season at USC after working alongside Kiffin, assistant head coach Monte Kiffin and defensive coordinator Ed Orgeron during their lone season at Tennessee.
Garza was a four-year starter at corner and safety at Texas from 1988 to 1992 and a graduate assistant with the Longhorns from 1994 to 1997. He has also coached at Western Michigan, TCU, Tarleton State and North Dakota State.
Graduate assistant Sammy Knight, who has worked extensively with Trojan safeties, would be the obvious candidate to replace Garza. Monte Kiffin could also take on a larger role coaching the defensive backs.