Can the ddo be arrested? what should he do ?

Although the facts are sketchy but it is clear that fraud has taken place with/without knowledge of DDO.  DDO can be (rather will be arrested) he should try for bail.

y9ou have not decribed that whet events preceded befor ethe case going to court.

In Govt system neither the DDO nor the authroising officer is the sole persons to deal with the bill, there is a heirarchy. What is needed to be seen is :-

1. When one denied his signature then there has to be forensic report on the same.
2. How large is the deptt whether DDO could know each and every peson.
3. For what purpose the bill was there.
4. What were the supporting orders of bill (i.e. transfer/tour order for TA/DA bill, Medical papers for medical reimbursement bill, bills for contigancy purchase bill)
5. whether other bill s passed by this DDO have also been disowned.
6. whether the bill bears finger prints of the persons denying his signature.
7. who exatly has written the bill.
8. who is beneficiary of bill.
9. how many hands the bill has cross from wrting to passing by DDO
10.