He died two days later, the 23d victim under age 18 to be killed by gunfire in the Philadelphia region this year.
In a city where terrified witnesses refuse to come forward, Hayes and his family were willing to testify while seeking some measure of protection for themselves.
Earlier this week, two witnesses in the shooting death of 5-year-old Casha'e Rivers recanted statements they had given police linking a defendant to the shooting.
No arrests have been made in the death of Hayes, and police say they don't know whether the homicide was related to his status as a witness.
Facing charges in the attempted arson is Alexander Wade, 20, who lived five blocks from Hayes' home. He has been in prison for months.
Wade's case had been scheduled for trial Nov. 27, and his attorney, Arnold Silverstein, went to court that day to argue that several of the charges against him should be thrown out.
Silverstein was surprised to learn from an Inquirer reporter this week that a witness had been killed.
"Oh, my God, I'm hearing this literally for the very first time," Silverstein said.
Hayes' mother, Barbara Clowden, 38, believes the attempt to set fire to her home was fueled by a dispute between Hayes and others in the neighborhood, maybe "over a girl."
Testifying last December at a preliminary hearing, Hayes said he looked out the window and saw gasoline being poured on the family's front door.
Police arrived before a blaze was ignited.
Clowden said she asked that her family be placed in the witness relocation program after her son was threatened and assaulted. This fall, she said, she enrolled Hayes' 14-year-old brother in "cyber-school" to help keep him safe.
Hayes, however, traveled through the city on a daily basis. Assistant manager Damien Williams said the teen had been working full time at McDonald's for 13 months - first at 60th and Woodland Streets, near his old house on Paschall Avenue, then at the Island Avenue fast-food store where he was promoted to crew leader.
According to Clowden, the witness relocation office may have been unaware of Hayes' continued employment so close to his old home. "I'm not sure if they even knew," she said.
Williams had no idea that the quiet, humble, helpful teenager he supervised was a witness and possibly in danger.
"We didn't know that," he said. "Oh, my God, no! The kids told me that he was supposed to testify against somebody, and I was like, 'Well, why would he still be working in this neighborhood?' Relocation to me is another state, not another neighborhood."
Unlike the federal Witness Protection Program, which has the budget to bestow new identities in faraway states, Philadelphia's program is a modest effort, relocating about 50 families a year and fighting for funding to do even that.
The District Attorney's Office, which oversees the witness relocation program, declined to comment on Hayes' death because an open homicide investigation is involved.
After Hayes was killed, Williams said, other teens working at McDonald's told him that some people in the neighborhood "were saying he was a big snitch, he got what he deserved."
Williams said that had he only known of Hayes' situation, he would have helped the boy: scheduled him differently, put him to work at a location safer for him - maybe at the airport - or "just talked him into doing something totally different."
On Saturday, a police patrol car watched over Hayes' funeral, where mourners expressed anger and frustration.
"Witness protection should be like the Secret Service with the president," said Daniel Brown, a family friend. "They shouldn't let him out of their sight until the thing is over."
Contact staff writer April Saul at 215-854-2872 or firstname.lastname@example.org.