A 38 year old Lansing man will be spending the rest of his life behind bars when he's sentenced next month for the death of his infant daughter.  An Ingham County jury took less than a day to find John Sanders guilty last night of first-degree murder and first-degree child abuse.  He is believed responsible for causing a severe head injury to the 3 month old girl whom he was caring for alone back in January.  The child's mother took the stand in the trial but Sanders did not.  He has never offered an explanation on how the child became injured.  A conviction on first-degree felony murder in the State of Michigan is mandatory life without the possibility of parole.  The child's mother and other family members are expected, though, to make victim impact statements before the sentence is imposed.