LOS ANGELES (CBS) —  A gang member was convicted of first-degree murder Wednesday for gunning down a standout Los Angeles High School football player who was about 40 steps from his home when he was shot.

Prosecutors are seeking the death penalty for Pedro Espinoza, 23, who killed 17-year-old Jamiel Shaw Jr. on March 2, 2008. A penalty phase of trial will be held for jurors to recommend whether Espinoza should be sentenced to death or life in prison without the possibility of parole.

READ MORE: LA County Increases Water Usage As State Drought Conditions Worsen

Jurors reached their verdict after deliberating four hours.

The jury found true the special-circumstance allegation that Shaw’s killing was carried out to further the activities of a criminal street gang, along with the allegation that Espinoza personally and intentionally discharged a handgun.

Prosecutors said Shaw was gunned down while walking home carrying a Spider-Man backpack, the red color of which made Espinoza perceive Shaw as a gang rival.

“We are here today because on March 2nd, 2008, he chose to take the life of Jamiel Shaw II,” Deputy District Attorney Allyson Ostrowski told jurors during a closing argument, noting that the last thing the teenager heard before being shot in the abdomen and then in the head was the classic gang challenge, “Where are you from?”

“It was a cold-blooded murder. It was an execution,” the prosecutor said.

READ MORE: Nearing Historic Strike Vote, Thousands Of Hollywood Workers Could Walk Off Sets Nationwide

But one of Espinoza’s attorneys, Csaba Palfi, countered, “I would describe this case to you as weak because of the inconsistencies.” He accused the prosecution of ignoring “a lot of facts” and said of his client, “Just because he’s a gang member doesn’t mean he did it.”

“There’s no charge for being a gang member. There’s no charge for standing up for your gang,” Palfi said, urging jurors to give his client “a fair trial.”

“I submit to you there is more than ample doubt in this case, ample doubt, and it’s reasonable,” the defense attorney told the panel.

Jamiel Shaw Sr. and his wife, Anita, unsuccessfully sued the county after their son’s slaying, alleging that Espinoza was a “dangerous felon and an immigration violator” who should have been turned over to immigration authorities rather than being freed from jail two days before the shooting. He had been serving time for assault with a deadly weapon.

The Shaws also mounted an unsuccessful petition drive aimed at getting a law passed that would enable police to arrest undocumented-immigrant gang members and hand them over to federal authorities.

MORE NEWS: LAPD Says Armed Robberies Have Become An Alarming Trend

(©2012 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. Wire services contributed to this report.)