Judge, David Radford warned Mary Konye that she will face jail when he sentences her on March 7:
I should make clear that, in my judgment, this is a case that will, in all likelihood, need a substantial custodial sentence. It is inevitable, but it won't be dealt with until I have received those reports.
Victim, Naomi Oni burst into tears as she left the courtroom and was hugged by family and friends.
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"All it takes is for somebody to see me - and I could just die, just like that. I could want to go to the shop and not come home."
Before the killing, Peters searched the internet for "serial killers", "treatment of child killers in prison" and "premeditated murder".
Arriva Rail North, Greater Anglia and South Western Railway are all affected.