The father of a 13-year-old girl who was stabbed to death in a park has said her murder "means we will never have the privilege of her in our lives again".
Anthony Kearney was speaking as Hannah Bonser, 26, was jailed for life for the murder of his daughter Casey and told she must serve a minimum of 22 years in prison.
Casey Kearney was stabbed by Bonser - a total stranger - in Elmfield Park, Doncaster, South Yorkshire, on Valentine's Day and died later in hospital.
Casey was heading for a sleepover at a friend's house when she was stabbed once by Bonser with a 16cm kitchen knife the defendant had bought earlier.
The teenager called 999 but only managed to say she had been stabbed. Medics fought for hours to save her but she died later that day of severe blood loss.
Bonser, of Cusworth House, Doncaster, denied murder. She has a long history of mental health problems and cannabis abuse and her defence team claimed she is a paranoid schizophrenic.
Her barrister, David Fish, asked the jury of seven women and three men to find his client guilty of manslaughter due to diminished responsibility or lack of intent.
But prosecutors argued the 26-year-old suffers from a personality disorder, not a psychosis, and was guilty of murder. The jury agreed.
Sentencing her, Judge Mr Justice Cranston said: "Why did Hannah Bonser do this to Casey - a young girl, a complete and wholly innocent stranger?" He said she suffered a "horrific death".
Speaking outside court, Mr Kearney said: "We think the jury has come to the correct decision in convicting Bonser with the murder of Casey. There was never a doubt in our minds this was a calculated and deliberate act and therefore deserves the maximum sentence our judicial system allows. However, no sentence will bring Casey back to us and the severity of Bonser's actions mean we will never have the privilege of her in our lives again."
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