21 year old dating a 16 year old
Police were called to Alness Drive in the Woodthorpe area of York on January 9 at about 4.30pm and found the fatally wounded girl lying near a football pitch.
She was rushed to York Hospital with significant lacerations to her neck and chest but despite doctors' best efforts they were unable to save her.
She was reported to have no heart output but resuscitation attempts continued until they arrived.'However, attempts to revive her failed and she was certified dead at 5.44pm.'The defendant was detained at the Mills' house.
She appeared upset and was crying and the officer who arrested her also thought she was in shock.'All she would say is she had been on the field.
Nicholas Johnson QC, defending, asked the court if the charge of murder could be put to the girl again and she wrote her plea on a piece of paper.
The court heard the defendant's mental health had nosedived in the 12 months leading up to killing and she had developed an unhealthy interest in the 'macabre'.
Leeds Crown Court also heard today that police searching her bedroom found a toy Simba from Disney film The Lion King with 'its ears ripped off and stuffed inside the animal's chest through a large gash'.
She had been self-harming and was under the care of Child Adolescent Mental Health Services.
The teenager was prescribed fluoxetine for anxiety and depression in December 2016.
The next month, Katie was found with severe and large cuts to her neck and chest on a playing field in York - before the teenager was arrested and charged with murder.