michael shepard , 35 , conned parents into believing he was n't dangerous and even convinced them to let him babysit , police say .
he raped and sexually abused at least seven children , including a girl as young as five , authorities allege .
at a hearing to keep him locked up , one psychologist testified in his defense , the other said he was ` on the fence ' about keeping shepard behind bars .
shepard spent 15 years in prison for sexually abusing two boys and has a history of sex offense dating back two decades .