Stringer is the second person to be tried and convicted for the Jan. 19 murders of Breon Taylor, 15, of Los Angeles, and Dennis Moses, 17, of Long Beach, at the Masonic hall in the 5900 block of Parkcrest Street.
Co-defendant Izac McCloud, was convicted by a separate jury on September 16. Jurors found him guilty of two counts of second-degree murder and 46 counts of assault with a firearm.
Stringer and McCloud were indicted in August 2008 in connection with the killings. Prosecutors say Stringer got into a fight at the party and yelled at McCloud to "get them." Investigators say shots were fired from a 9mm semiautomatic gun in the parking lot into the hall where more than 400 people had shown up for a party originally intended for 100 guests.
McCloud is set to be sentenced Oct. 7 by Long Beach Superior Court Judge Mark Kim, and is facing 200 years to life in prison.
Stringer is facing a maximum of 198 years to life in prison, with sentencing set for Nov. 16.