Kless' life was cut short Saturday when, police said, three men beat him to death on the steps of the historic Second Bank of the United States on Chestnut Street. His assailants smashed his head against a low granite wall in front of the bank building.
The 23-year-old native of Warwick, N.Y., died shortly afterward at Thomas Jefferson University Hospital.
On Sunday, police continued their search for the assailants, who apparently attacked Kless after a misunderstanding over hailing a cab. No arrests had been made.
"It's so senseless, such a tragic waste of a wonderful young man," his mother, Kendall Kless, said in a telephone interview from their home in Orange County, N.Y.
The youngest of three boys, Kless graduated from Temple's Fox School of Business with a degree in risk management and insurance.
At Temple, Kless was involved in the Sigma chapter of Gamma Iota Sigma, an international professional fraternity whose members include risk-management and insurance majors, said R.B. Drennan Jr., Kless' former professor and the fraternity's faculty adviser.
Drennan said Kless had recently left his first job out of college with an insurance firm in Harrisburg and had taken a position in the Philadelphia office of Marsh, a major insurance brokering and risk-management company.
"It's quite competitive to get a job at Marsh. That's a feather in his cap that he was able to do that," Drennan said.
Drennan called Kless "a good ambassador for the program."
"Had this not happened, he would have continued to have a successful career. I have no doubt about that," Drennan said.
Just before 2:25 a.m. Saturday, Kless and two female friends were walking on Chestnut Street near Fourth Street when he tried to hail a cab. The bars had just let out, and the three had just left Lucy's Hat Shop Restaurant & Lounge a few blocks away.
The cab's rooftop lights were on, signaling it was available, but there were passengers inside, and the taxi didn't stop. Police said Kless yelled, "Turn off your f-ing lights."
A maroon Mazda with four men inside drove up behind the cab as traffic likely slowed briefly.
The people in the Mazda may have thought Kless was yelling at them, one investigator said. It is not known whether Kless and the men exchanged words.
Two men got out of the car and attacked Kless, who was walking arm in arm with his girlfriend, near the bank steps. One of Kless' companions said Kless tried to protect the women from the attackers. For a few moments, his attackers beat him as his friends cried for help.
The a third man got out of the Mazda, and the attack resumed with greater ferocity, investigators said. The assailants smashed Kless' head against a low granite wall in front of the bank building, police said.
The men then drove off. A security camera captured an image of the Mazda 626, which police described as a four-door sedan, possibly from the 2000-2003 model years. Police were reviewing security footage, Lt. Ray Evers said.
National Park Service rangers stationed nearby responded to the women's cries and rushed to help Kless, Evers said. Kless had no pulse, he said. The rangers administered CPR and used a defibrillator until paramedics came.
When Kless' family arrived from New York, nearly a dozen of his friends were already waiting at Jefferson.
"Some lady just walked by and said, 'I've never seen this many people in the waiting room,' " his mother said.
Her son was excited about his new job and reconnecting with friends. He was athletic and loved California - San Diego, in particular - because other friends lived there and the weather didn't interrupt his outdoor recreation.
His oldest brother, Matt, 29, said Kevin Kless excelled at baseball and snowboarding.
"There wasn't a person in the world that he couldn't befriend," Matt said. "Kevin was an innocent young man who did not deserve to have his life cut short. The world just lost an amazing person."
His mother pleaded with witnesses to come forward.
"How do you walk by someone getting pummeled to death?" she asked. "He was funny, he was handsome, he was smart, and now he's gone. Why?"
Anyone with information about the beating is encouraged to call homicide detectives at 215-686-3334 or 911.
Contact staff writer Darran Simon at 856-779-3829, firstname.lastname@example.org, or @darransimon on Twitter.
Inquirer staff writer Mike Newall contributed to this article.