New York police say a teenage robber shot his victim dead when he was about to hand over his valuables.
They claim the 15-year-old thought the man was pulling a gun out of his pocket and not a gold chain.
The man was sitting on a Central Park bench with a female friend when the attack happened. The boy and two accomplices have been charged with murder.
The woman who was with 25-year-old Ismael Marzan said the boy told him to take off his jacket.
"But he didn't even give him the chance. He shot him," she said.
The woman added: "I can't even close my eyes without seeing him lying on the ground."
The boy's grandmother, who's cared for him since he was a baby said: "My heart is torn apart. I can't stop crying for that family."