A teenager who killed a seven-year-old girl in a park when she smothered her and slashed at her body with a knife is to be sentenced today.
Katie Rough was found with severe lacerations to her neck and chest on a playing field in York in January.
But Leeds Crown Court heard earlier this year how she actually died from being smothered by her attacker - a 16-year-old, who cannot be named for legal reasons.
The court heard how the teenage killer was covered in blood and carrying a blood-stained Stanley knife as she rang 999 to tell police what she had done.
She may have been trying to prove the youngster was not a robot, as she had 'irrational beliefs' about how people 'may not be human and may be controlled by a higher and hostile force', the court was told.
The killer denied murder but pleaded guilty to manslaughter by diminished responsibility.
The judge has heard how she began suffering from mental health problems more than a year before the killing.
Prosecutors said she had reported delusional thoughts as well as depression, self-harm and suicidal thoughts.
They said the girl had talked of being convinced that people 'weren't human and were robots'.
He said the girl became distressed when one doctor asked her later 'whether she killed Katie to test whether she was a robot'.
The court heard that, although psychosis was being investigating prior to the killing, it had not been diagnosed.
Nicholas Johnson QC, defending, told the last hearing it was possible his client was 'driven by the irrational belief (Katie) may not have been human and needed proof of this'.
He said the teenager had thoughts that people around her 'may not be human and may be controlled by a higher and hostile force'.
The barrister said his client had posted a picture on social media two days before the killing with a concerning message.
He said: "She was clearly crying out for help and support."
In July, the judge said he wanted more questions answering by medical experts before he could pass sentence, and apologised to Katie's family for the delay.