'I'll kill anyone who crosses me, vowed woman who knifed girl aged 13 to death Mr Reeds said: "It cannot be known why Hannah Bonser went to the park that afternoon. She later declined to answer police questions and she now claims to have no memory of what she did. He said Casey, from the village of Rossington, near Doncaster, had been on her way to visit a friend and missed her intended stop on the bus. She continued her journey on foot and Miss Bonser stabbed her without warning as she passed her in the park, the court heard. "As they approached each other, the defendant pulled out the larger of her two knives," Mr Reeds said. As she came alongside Casey, the defendant stabbed her once in the abdomen, causing such severe internal injuries that Casey later died. The attack was sudden and caught Casey completely unawares. There was no argument, no shouting, there was no warning that anything was about to happen. Two 10-year-old children in the nearby playground heard no screams and saw no signs of any struggle. After the attack, Miss Bonser walked away from the park, the court was told. Casey collapsed but managed to call 999 on her mobile phone. "All she could say was that she had been stabbed," Mr Reeds said. It is alleged that after the attack Miss Bonser went to an office of Rethink, a mental health charity, and told an outreach worker she had killed somebody. She is said to have produced two knives, one of which, with a 6.3in (16cm) blade, had Casey's blood on it. Mr Reeds said blood was later also found on the inside of Miss Bonser's sleeve. The prosecutor said this indicated "that after she had stabbed Casey with that large knife, the defendant deliberately secreted it up her sleeve so as not to draw attention to herself as she walked out of the park." Mr Reeds said the defendant intended to kill the girl, or cause serious harm. Opening the case earlier, he had said: "Hannah Bonser is a woman with a troubled history, who was in regular contact with outreach workers at Rethink, which is a service which assists those in Doncaster with mental health difficulties. In October 2011 she had spent a short time in a psychiatric hospital in Doncaster. The trial continues.