The son of a retired San Francisco sheriff's deputy was convicted of murder Friday for what prosecutors portrayed as a revenge slaying intended to prevent the defendant's former best friend from testifying against him in another criminal case.

Philip Sands, 26, of San Francisco showed no reaction as the jury verdict was read finding him guilty of first-degree murder with special circumstances in the July 12, 2003, shooting death of his onetime friend from Sacred Heart High School, 24-year-old Robert Ramirez of Daly City.

Ramirez's family wept and embraced each other as the verdict was read in San Francisco Superior Court.

"It's justice -- I believe in the justice system,'' said the victim's mother, Debbie Crowley Ramirez.

Sands took the stand during the trial and proclaimed his innocence. Prosecutors said they had a "mountain of evidence'' to indicate he was guilty, including the fact that the murder weapon was found at a relative's home and the existence of wiretapped phone conversations that suggested he had fabricated an alibi. Cell phone records put him at the scene of the slaying.

Sands' attorney, J. Tony Serra, said after the verdict: "I persist in the belief that there was and is reasonable doubt.''

The same jury that took 11 hours over two days to find Sands guilty also convicted him of assault and other charges in a stabbing Sept. 14, 2001, near what was then called Pacific Bell Park. It was that case, prosecutor Ana Gonzalez contended, that set in motion the events that led to Ramirez's death.

Sands had been accused of stabbing Robin Clarke, a computer programmer who Ramirez had bumped into outside a bar. After Sands was arrested, police told him that friends had implicated him.

As the case approached a preliminary hearing in 2003, Sands -- by this time out on bail -- became convinced Ramirez was going to testify against him, prosecutors said.

Ramirez was killed after the car in which he was riding ran out of gas near the Ocean Avenue off-ramp of Interstate 280. Prosecutors said Sands learned in a phone call that Ramirez was stranded in the parking lot of San Francisco City College, then drove from his home in the Sunset District and sprayed the car with 30 rounds just before 4 a.m.

Sands was the only defense witness. He said a man had called him about Ramirez that night who was responsible for the killing. Sands said the man told him he had "taken care of business" and had given him the murder weapon, a machine pistol capable of firing 30 rounds. Sands said he had later given the gun to a relative for safekeeping.

"I didn't commit this murder," Sands testified. "Everybody is trying to put this on me, but I swear to God, I didn't do it, I didn't kill anybody. I didn't kill Robert Ramirez.''

Sands said that although he was upset at Ramirez after the stabbing, he did not believe police when they told him that a friend had implicated him.

Sands grew up in the Sunset, the son of a now-retired 20-year veteran sheriff's deputy. Sands and Ramirez had known each other from St. Cecilia's parochial grammar school, and both were later in a group made up mainly of Sacred Heart students that called itself Sunset District Inc., or "the Bros."

The jury verdict against Sands included a conviction for killing a witness in a criminal case, which carries a sentence of life without the possibility of parole. District Attorney Kamala Harris has promised never to seek the death penalty.

Sands will return to court on Nov. 18 for a pre-sentence conference.