LOS ANGELES, Calif. - A gang member who killed a promising Los Angeles High School football player because he believed the athlete's red Spider-Man backpack linked him to an opposing gang was sentenced to death on Friday.

Pedro Espinoza had told authorities he was willing to kill for his gang, even if it meant going to death row.

Superior Court Judge Ronald H. Rose imposed that very sentence — ordering Espinoza taken to San Quentin State Prison. The judge rejected defence arguments that the 23-year-old didn't get a fair trial.

"The evidence is clear he decided to murder the victim in cold blood and bragged about the killings after," Rose said. "The defendant executed the victim as he lay on the ground defenceless."

Jamiel Shaw II was a 17-year-old standout running back when he was gunned down in 2008. He was not a gang member.

His parents and friends appeared in court Friday wearing red. They said it wasn't to symbolize a gang — but for "the blood spilled."

"You don't have a right to execute someone and then come in and plead not to be executed," said Jamiel Shaw Sr., the father of the victim.

Shaw said he devoted his life to preparing his son for a brilliant athletic career.

"We really thought we had a chance," he said. "My son was groomed to succeed."

Anita Shaw, a U.S. Army sergeant, told of being in Iraq on her second tour of duty when she was summoned by her commander and told that her son had been murdered.

"I lost it," she said. She invoked scripture, saying she knew she was supposed to forgive — but "I'm not that strong of a person."

Espinoza didn't move and didn't look at Shaw's parents as they spoke.

The judge noted that Espinoza had been released from jail shortly before the killing on an unrelated charge and had been counselled by an officer who warned him of the consequences of further criminal behaviour.

Rose urged the family to focus on raising their 13-year-old son, Thomas, who also attended the sentencing. Shaw said outside court he would do that but feels the gang situation has changed parenting.

"You're not raising them anymore," he said. "You're trying to keep them alive."