CHICAGO (AP) — Again and again defense attorneys and prosecutors played the same graphic video of 16-year-old Derrion Albert being beaten to death — grainy, shaky and just a few minutes long.

The two sides disagreed about whether it showed that Silvonus Shannon had kicked the Chicago high school honors student in the head. But it was enough for jurors to convict Shannon of first-degree murder on Tuesday night, making him the second person found guilty in the September 2009 attack.

“The truth is the truth,” Albert’s grandfather, Norman Golliday, said after the verdict was announced. And the truth, he said, was that the video showed Shannon helped kill Albert. “It’s obvious.”

Shannon faces a sentence of as long as 60 years in prison when he returns to court Feb. 14. Three more people still face charges in the attack that drew international attention when video of the street brawl was posted online.

Shannon and his lawyers contended he was acting in self-defense, that he was trying to stop the fight and that he fought only after he was attacked himself by a number of young men — including Albert.

Prosecutors disputed that account and contended Shannon’s was the final blow in the fatal attack.

The video shows a group of young people kicking and hitting Albert. At one point, someone slams a board into Albert’s head, then Shannon appears to prepare to kick the fallen teen. But Shannon told jurors he had no recollection of striking Albert.

The video also was the centerpiece of prosecutors’ case in the trial last month of a juvenile convicted of first-degree murder in Albert’s death. It is likely to be played again at trials for the three others, all of whom are charged as adults.

Shannon took the verdict quietly. Hours after speaking on the witness stand, sometimes in almost a whisper that could barely be heard, he silently dropped his head, put his head in his hands and wept.

A few feet away, his family members cried as well, as did the mother of Albert on the other side of the courtroom.

“We empathize with the families of the gentlemen who have been charged, but we are grieving for our loss still,” Golliday said afterward, speaking for Albert’s family. “We’re praying to move forward, but realistically that probably won’t happen until justice is served and all responsible are held accountable.”

The case marked the most vivid example of escalating violence that in a six-month period claimed the lives of more than 20 Chicago public school students. It also prompted President Barack Obama to dispatch top Cabinet officials to Chicago to discuss ways to quell the violence.

Shannon acknowledged in his testimony that the video shows him bending his legs and leaping more than a foot into the air as Albert lay nearby in the street. Where he lands is obstructed in the video by a bystander.

“The tape don’t show me landing on his head,” Shannon told Cook County Assistant State’s Attorney Kathleen Bankhead. “I don’t think I would try to purposely land on anyone’s head.”

But Bankhead relentlessly went after Shannon’s account, replaying the video to make her point. Bankhead asked Shannon about what she called a “punter’s walk” toward Albert’s head as the teen lay on the ground. The prosecutor then asked Shannon if he could see Albert’s head move as the video showed Shannon moving in after someone else struck Albert with a board.

“Yes, ma’am,” he said quietly, but said the movement was caused by the board.

Defense attorney Robert Byman said his client was simply trying to get home from school when he came upon the street fight. He characterized Albert as a willing participant in the brawl, which Byman said stemmed from an earlier dispute between teens at nearby Fenger High School. Shannon was a student at the time.

During closing arguments, Cook County Assistant State’s Attorney James Papa pointed to the video and said Shannon clearly wasn’t acting in self-defense.

“He sticks around, he waits for his opportunity to strike,” Papa said. “Who is he defending himself from? He had ample opportunity throughout that entire incident to get out.”

Copyright 2011 The Associated Press.