(CBS/AP) CHICAGO - A Cook County jury on Tuesday found a fourth person guilty in the beating of Chicago high school honor student Derrion Albert, whose videotaped death in Sept. 2009 prompted nationwide outrage.
After 90 minutes of deliberations, the jury convicted Eugene Riley, 20, of first-degree murder in the death of the 16-year-old Albert, who was a Fenger High School sophomore.
Afterward, Albert's grandfather, Norman Golliday, said the family believes the verdict was "just and true." He added the process has become toxic for family members because they were going through it again and again.
In a cell phone camera video, Albert is seen being punched, slammed over his head with large boards, kicked and finally stomped on his head.
The sight of Albert, trying to defend himself against waves of attackers, being knocked to the ground, staggering up and unable to cover his body from all the kicks and punches, prompted the Chicago Police Department and the school district to take steps to increase security around schools. At the same time, in Washington, President Barack Obama dispatched two top Cabinet officials to the city to discuss ways to quell the violence.
"Each of those blows, each of those massive hits to Derrion Albert's head, contributed to his death," Assistant State's Attorney James Papa said in his closing arguments earlier Tuesday.
Papa contended Riley could have walked away when he saw Albert, 16, being repeatedly kicked in the head as he lay on the ground the afternoon of Sept. 24, 2009. He said instead, Riley further inflamed mob action by taking a large wooden board and slamming it down hard on Albert's head.
Riley testified Monday he only hit Albert because he was trying to defend a younger brother who had been knocked unconscious with a brick.
"It was a reaction. I was scared. I didn't know what was going on. I wasn't thinking," Riley said.
Papa pointed out Albert, who was unarmed, was already on the ground and being struck by others when Riley attacked him. Assistant Public Defender David McMahon argued Riley, then 18, made a "mistake" and "never meant" for Albert to die.
A juvenile and two adults were previously convicted in Derrion Albert's death, and one other adult has pleaded guilty to first-degree murder.
The last defendant in the case, Lapoleon Colbert, is scheduled for trial later this month.