Carrillo was one of three men charged in Kless' beating death last Jan. 14 in an early-morning altercation at Fourth and Chestnut Streets in Old City.
He was the first to plead guilty - to involuntary manslaughter - in a deal with the District Attorney's Office that specified the prison term.
But before Common Pleas Court Judge Benjamin Lerner could impose sentence, Carrillo listened to about 21/2 hours of angry and mournful testimony as Kless' family - and his own - tried to make sense of the senseless.
Carrillo, a gaunt man in a dark suit, sat solemnly, eyes closed, as emotion roiled around him.
"I want to apologize to Kevin's family and friends," Carrillo told Lerner before sentencing. "I really wish I could go back to that night. But I can't."
Carrillo's mother, Elizabeth Rivera, and two aunts also tearfully apologized to the Kless family and friends.
Lillian Ortiz, one of Carrillo's aunts, could barely control her emotions as she told the Kless family how her own nephew had been murdered.
"Who would ever believe that the poor choice made that night would devastate and affect so many people?" Ortiz added, referring to Kless' killing.
Many of the 50 members of Kless' family and friends who packed the courtroom seemed inconsolable and unconvinced.
Tim Holland, whose daughter Kerri, Kless' girlfriend, was walking with Kless when he was assaulted, called the incident a "sneak-attack ambush" and said his daughter was still in shock.
Holland said he did not believe that Carrillo was truly remorseful: "He's sorry - he's sorry he got caught."
Matthew Kless, Kevin's oldest brother and an Air Force captain, wept and called the plea deal and sentence a mockery of justice.
Wearing his blue dress uniform, Kless referred to his military service and glared at Carrillo: "I'm risking my life protecting the very man who tore my life apart."
As Kless returned to the gallery, his father, John, rose to embrace him and erupted in a loud sob.
"He is not a case number, he is not a news story," said Kless' mother, Kendall, holding up his photo. "He is my son. And I want him back."
Lerner and Assistant District Attorney Brendan O'Malley defended the plea agreement and sentence.
O'Malley said that five years was the maximum for involuntary manslaughter, a misdemeanor, and that two years was several times the three to 12 months recommended by state sentencing guidelines.
Defense attorney Scott P. Sigman noted that Carrillo gave a complete confession within 30 minutes of arrest and did not throw the fatal punch.
Two other men arrested with Carrillo - his cousin Kenneth Enriquiz-Santiago, 20, of Juniata Park, and mutual friend Steven Ferguson, 21, of Fox Chase - are free on bail pending trial on charges of third-degree murder.
Police said the fatal confrontation occurred after both parties spent the night clubbing in Old City.
Police said that Kless, Kerri Holland, and another friend were walking about 2:30 a.m. when Kless tried to hail a cab and cursed loudly when the taxi kept going.
Police said Ferguson and his two companions, in a car behind the cab, apparently thought Kless had cursed at them and stopped. The cousins got out of the car and allegedly began hitting Kless.
The cousins walked away and, authorities allege, Ferguson walked up and punched Kless once in the head, tearing a blood vessel in his neck and killing him.
Contact Joseph A. Slobodzian at 215-854-2985 or firstname.lastname@example.org, or follow on Twitter @joeslobo.