After a four-day pretrial hearing, a Los Angeles County judge found Friday that there was sufficient evidence to try Smith, a defensive end for the Los Angeles and Oakland Raiders from 1991 to 1998.
Smith has already been tried for one of the killings: the 2008 death of Maurilio Ponce, a mechanic found stomped and shot along a California desert highway.
A jury deadlocked in that case in April. While awaiting retrial Smith was charged with three more murders: The killing of two brothers in 1999, and another slaying in 2001. All four have been combined into one case.
Defence attorney Daniel Evans says there's no physical evidence tying Smith to any of the killings.