Signatures&right hand thumb impression taken without knowledge&consent

I had gone to a govt office to get a certificate after my father's death.Its employee asked me to sign 4-5 papers & right hand thumb impression.Employee tightly holded the papers on the table from his hand & turned the pages one-by-one only from the bottom side of the papers.He didn’t turn the pages completely as a result, I couldn’t see & read the contents of the pages.He didn’t remove his hand from the bunch of the papers.His supervisor started talking while I was signing the papers.Next day, I called employee & asked him on what all papers he took my signatures but he clearly refused that he gave me any such papers to sign.I went to the govt official's HEAD said that this matter is between me & employee.I had gone to police station but no complaint/FIR filed.My signatures & right hand thumb impression should not be misused by anyone.What all should I do so in future I'll be safe from any mishap?I told the govt official & his HEAD-I require the certificate formy property/legal matter