Prosecutors argued that Pace was targeting a rival gang member on board a CTA bus when he shot and killed Holt and wounded five others.
The shooting in May of 2007 on a CTA bus full of high school students prompted outrage against gun violence.
Police released the surveillance video of the shooting for the first time on Monday. The video shows a rash few seconds of violence that claimed the life of Blair Holt and led to a 100-year sentence for his killer.
The cameras mounted on the CTA bus clearly show Michael Pace jumping on the bus with the 40 caliber handgun drawn. He fires off several rounds as passengers dive for cover. Shots hit five of the passengers, including a bullet that proves fatal for 16-year-old Blair Holt. Seconds later Pace jumps off and runs from the bus.
It was the first time Blair Holt's mother could bring herself to watch it.
"I had to see what happened to my baby at the end before I saw him in the hospital laying on that table. So I had to do that. That was for me as his mom. If he was strong enough to do this, to give his life for somebody else, I was strong enough to endure to see it," said Annette Nance-Holt, mother of Blair Holt.
Pace pleaded guilty last month to first degree murder and aggravated battery. He avoided a trial but during Monday's sentencing he heard from victims and their relatives. Ron Holt called Pace a miscreant. "What were you thinking," he asked. "You didn't care who you shot." Pace listened but, according to Holt's family, showed no remorse.
"That smirk that he put out there today, he can smirk all he wants but it's going to be 100 years. He can smirk 100 years behind bars," said Ron Holt, father of Blair Holt.
Pace's attorney argued for leniency saying her client was a brain damaged juvenile.
"Michael's severe life long learning disability was not given the appropriate consideration that I would have hoped for," said Mary Danahy, Pace's attorney.
"I feel like both families and both of the young men involved were victims of the hardness of the world. I feel like 100 years was too stiff," said Patricia, Pace family friend. "He made a rash decision and poor judgement."
Judge Nicholas Ford discounted a psychologist's testimony for the defense about Pace's low intellectual ability. Prosecutors agreed.
"There are people with mental disabilities every day who make it through life and never hurt or harm another individual. So that's just a copout," said Annette Nance-Holt.
The 100-year sentence includes a total of 60 years for Blair Holt's murder and 40 more years for two counts of aggravated battery with a firearm. Michael Pace's attorney says she believed he would get 45 years. She plans to file an appeal.