The murder victims, Marine Sgt. Jan Pietrzak and his wife Quiana, were found bound, gagged and shot on October 15. Investigators say the home had also been ransacked.
Emrys John, 23, and Tyrone Miller, 25, were convicted of two counts of first-degree murder. The jury also found true the special circumstances of murder during the commission of a robbery and during the commission of a burglary and multiple murders.
Earlier in the day, a separate jury returned guilty verdict on the same counts for Kevin Cox, 25.
Prosecutor Daniel DeLimon said the three led double lives as "Marines by day, criminals by night." The men went to Pietrzak's home to rob him and physically assaulted him and sexually assaulted his wife before killing the couple, prosecutors said.
For Miller alone, the jury found true the special circumstance of rape by instrument.
Jurors now move into the penalty phase of the trial for all three men. They will decide whether the men should be sentenced to death or life in prison without the possibility of parole. The penalty phase will begin on Monday.
A fourth former Marine, 26-year-old Kesaun Sykes, faces the same charges and is awaiting a separate trial in the case.
Authorities say Cox, John and Miller worked with Pietrzak while stationed at Camp Pendleton. Pietrzak, a Brooklyn native, worked as a helicopter mainframe mechanic. He served in Iraq from July 2005 to February 2006.
The Associated Press contributed to this report.
