“They were just standing around, chitchatting, making jokes,” said 27-year-old neighbor Aaron Dunn, referring to the police. “They were just letting it bleed out. It had two gunshots in it. The owner was patting it with Kleenex.”Stephen said that a bystander lent her a cellphone, and that she called her teenage son, Aidan, who rushed to the park from Williamsburg. He arrived with friend, and quickly rushed home to get his mother’s wallet and cellphone. On his way back, he cut across the crime scene area. Multiple witnesses said they observed several police officers approach Aidan, push him against a tree, and arrest him. “The son is running through the park eastward, is obviously distraught, and the cops just grab him and throw him against a tree,” Dunn said. “They put him in handcuffs.””He was frantically saying he had to deliver the wallet to his mom, the cops would not let him pass and restrained him,” said neighbor Michelle Bilella.