Lydia Bishop is believed to have been dropped off at the nursery at York College Monday by her mother, Rebecca Dick, who had lectures, Daily Express reported.
Detective Chief Inspector Nigel Costello, of North Yorkshire Police, said: "I understand it was her first day of nursery. We have started to interview staff."
As families left flowers and cards on her demise, one of the cards read: "To a lovely little girl, rest with the angels."
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