In practice: A self drawn cheque can be encashed by anyone, if the drawer sign on both the side (endorsement on the back side by drawer) and the person who encashes the cheque also signs on the back side at the time of collecting the money. If there is no other signature on the back side, that means drawer only has collected the money, now the point in your case is that drawer could not have been physically present, then how the cheque reached Bank ??
1. Bank could not have given money to anyone without taking his signature on the back side.
2. If the money is still given without back signature and the drawer could not have been present, then Bank certainly goofed up, but the question still remains how come cheque reached the Bank.
3. In nationalised Bank there are two windows, first window for validation and entry and second window for cash withdrawal, generally signature of withdrawing person is taken at both the places, check if this was done.
In all likelyhood some other signature apart from two signatures of drawer in the front and back, would be there on the back side. Then I am sorry no case is made out.