EMBED >More News Videos Watch surveillance video of the moments surrounding the beating death of a homeless man in Mayfair.

57 year old Kevin Cullen fatally assaulted in Mayfair. His family says he was the 4th of 6 siblings, was deeply loved and is very missed. Search for teen suspects continues. pic.twitter.com/dYWRHycSm7 — Katherine Scott (@KScott6abc) November 28, 2017

EMBED >More News Videos Police: Teens pummel homeless man to death. Katherine Scott reports during Action News at 5:30 a.m. on November 28, 2017.

MAYFAIR (WPVI) -- The search for suspects continues following the brutal beating death of a man in the Mayfair section of Philadelphia.A surveillance camera captured the moments surrounding Sunday night's attack that left 57-year-old Kevin Cullen dead.Police believe a group of teens was behind the attack. Initially they had two in custody, but on Tuesday investigators said there have been no arrests.Now one of Cullen's family members is speaking out.Tom Cullen told Action News his younger brother grew up in Mayfair, the fourth of six children."Basically as he got older, he was my right-hand man," Cullen said.Tom said Kevin was very much loved, and he described the devastation the family is now feeling."He was viscously assaulted by a pack of youths," he said. "They beat him into unconsciousness, from which he never recovered."Shortly before 6 p.m. Sunday police were called to the 4200 block of Loring Street for a robbery.Officers found Cullen lying on the ground unconscious.The seconds before the brutal beating were recorded by a home surveillance video camera. The video shows Cullen being followed before he was attacked out of frame.One resident ran to help."They were laughing, like it was funny," that resident told Action News. "They hit his head into a wall so hard I felt it in my house on the second floor."Cullen died at the hospital early Monday morning. Police believe robbery was the motive.His brother said Kevin Cullen had no permanent address and would stay with various people.Since his father passed away 11 years ago, Kevin had a particularly difficult time and had his demons. But Tom said he was always in his family's hearts."We didn't get to see him too often. He would come in and out of our lives," Cullen said. "He was not abandoned, he was not unloved. He was loved deeply."Investigators say the teens behind the attack were wearing dark clothing. One had on a grey camouflage jacket.Anyone with tips is asked to contact the Philadelphia Police Homicide Division.----------