Haryana Minister Rao Narbir Singh on Thursday expressed shock over the recent development in CBI's investigation in connection with Pradyuman murder case that has found a class XI student of Ryan International School culpable of the crime and demanded an impartial probe into the matter. 'I still can't believe that it was done by a Class XI student. I would just like to reiterate that there must be an impartial probe so that everyone can make peace with the finding regarding who the real culprit is,' Singh told media here.