/*Kinta Stanton*/, 17, was found guilty of involuntary manslaughter and conspiracy.
All three had been charged with third degree murder.
The attack happened in March, 2008 in a subway concourse at 13th and Market Streets.
/*Sean Conroy*/ died of an acute stress-induced asthma attack during the beating.
It was the outcome Conroy's family had been praying for. They say the more they learned about his killers, the more this case screamed for justice, and they say they got it Tuesday.
The Conroys say they had been willing to forgive the boys who killed their only son, even hoping they could avoid jail time. But, when they saw the teens laughing their way through the trial, laughing and joking Tuesday with their girlfriends, they had a change of heart.
Now, Conroy's mother is hoping for a stiff sentence.
"Of course I'd like to see the maximum. I 'd like to see them off the streets of Philadelphia for a very long time," said Sharon Conroy.
"They planned this, they executed it down to the escape. They split up after they murdered my son so they would not be caught," said Sean's father Steven. "These are not innocent kids."
The three teenagers were led from the courtroom in handcuffs.
Their families left with no comment.
Stanton's lawyer was baffled by the verdict.
"It's a little upsetting because they heard him and I think they believed him," Lonny Fish, an attorney for Stanton, said of the jury's verdict. "I thought my client was innocent of all the charges."
The boys had claimed they did it on a dare, a test of their manhood...not intending to kill anyone.
All five teens had skipped school in North Philadelphia to head to a downtown mall, according to prosecutors. The teens were on the subway platform when someone challenged another group member to hit someone, and Conroy was punched from behind, authorities said.
A police officer soon observed four teens beating and kicking the man. By the time the officer got to him, Conroy was on his knees, gasping for breath. He was pronounced dead within the hour.
All three defendants told police they didn't hit Conroy, but Stanton was the only one to take the stand in his own defense.
Defense attorneys argued that the teens lacked the malice required to convict them of third-degree murder. Messages left by The Associated Press with attorneys for Best and Fisher were not immediately returned Tuesday.
Two other teens previously pleaded guilty in the case: Raheem Bell, 17, and Arthur Alston, 18. They are still awaiting sentencing.
The Associated Press contributed to this report