Dwight Campbell, 26, and Clifton Wherry, 31, were also convicted of the special circumstance of committing a murder during the course of a robbery for the incident, which occurred in the 2300 block of East 10th Street on Sept. 29, 2006.
Campbell, who's from Southern California, and Wherry, an Oakland man, face life in prison without the possibility of parole when they're sentenced by Alameda County Superior Court Judge Larry Goodman on Dec. 11.
Wherry worked for Brinks and was the driver of the armored truck that day. Prosecutors alleged he was the mastermind behind the robbery.
A large group of family members and friends of Quintero, 24, who had served in the Marines, cried when an eight-woman, four-man jury delivered its verdict after deliberating for two days.
His sister, Desiree Quintero-Ray, who wore a T-shirt bearing a photo of Quintero in his Marine uniform and his birth and death dates, said, "This is a joyous and a sad day for all of us. Justice has prevailed."
Campbell also served in the Marines. Campbell's attorney, Lorna Brown, said in her closing argument on Monday that he'd had a hard time finding a steady job after being honorably discharged and was recruited by a third man, William Stallings, another former Marine who had been his sergeant in Iraq, to participate in the robbery.
Prosecutor Mark Jackson said in his closing argument that Wherry was the brains behind a plot to kill Quintero and steal the money and that Campbell was the muscle.
Brown admitted that Campbell shot and killed Quintero but claimed that a shotgun that Campbell was carrying went off by accident when Wherry suddenly stopped the armored truck.
Brown said Campbell thought his role would only be to move money from one location to another and that he wouldn't be technically involved in a serious crime.
She said Campbell's character is "unassailable" and that he "got into a terrible situation and was in over his head."
Jackson alleged that Wherry intentionally failed to follow Brinks procedures by not sounding an alarm when he was confronted by an armed man, Campbell, and gave his dispatcher the wrong information about the location of the robbery, delaying the police response and giving Campbell and Stallings time to get away.
But Wherry's lawyer, Tony Serra, said in his closing argument that Wherry didn't know a robbery would occur and is "almost like a choir boy."
Serra admitted that Wherry didn't sound an alarm but said Wherry was "petrified with fear" and "was doing the best he could under the circumstances."
After the verdict today, Serra said he believes Stallings was the mastermind behind the incident and he was upset that Judge Goodman didn't allow defense lawyers to present much information about Stallings' role in the crime.
Serra alleged that prosecutors "made a deal with him" and allowed Stallings, who had been arrested on a murder charge, to go free after he returned most of the money that had been stolen.
But Jackson said, "There is no deal between the prosecution and Mr. Stallings" and the case against Stallings is pending. He said prosecutors can't bring a case against him until they have sufficient evidence.
Quintero-Ray said she's upset that her brother was killed in an incident involving fellow Marines.
"Marines are supposed to have a bond to protect their brothers," she said. "It's so sad it happened."