A 16-year-old boy accused of fatally stabbing nine-year-old Aria Thorpe claimed the fatal injuries were caused during a “play fight”, the BBC reports. The teenager has denied murder and manslaughter charges over the death of Aria at a house in Weston-super-Mare, North Somerset, on December 15 last year.Prosecutor Ray Tully Casey told Bristol Crown Court that the defendant admitted he was holding the knife when the fatal injury occurred. Prosecutors said he claimed he was trying to scare Aria and expected her to panic when he swung the knife toward her.A post-mortem examination found that Aria died from a single stab wound, which penetrated her heart and punctured her lung. Medical evidence indicated that the injury required at least mild force.Jurors heard that after the incident, the teenager went to a nearby train station and told a group of youths that he had stabbed a child.He reportedly said, “I was playing with the knife. She went near the knife. I accidentally attacked her with a very big knife.”The court heard he also called himself a “killer”, said “I’m done… why did I do this?”, and searched online for “what would murder do” after borrowing the phone.A young man alerted the police at the station. The teen later boarded a train but was found and arrested by authorities.Prosecutors said that although the boy later expressed remorse during police questioning, he did not initially mention any play-fight or claim that Aria had stabbed him.In a statement, he told detectives: “I picked up a knife and stabbed him in the chest. I didn’t use a lot of force, but it was a big knife. I don’t know why I did it, it just happened.”