taylor lynn fast , 21 told police in festus , missouri , that 17-month-old layla was bruised and unresponsive because of the bite , officers said .
fast allegedly claimed she had been bitten a day before police were called on sunday .
according to the fox2 local news station , layla had severe injuries to her face and neck , and was bruised all over .
paramedics who attempted to treat layla at the scene said she was dead for several hours .