Cheque bounce

The fact that a person has been held guilty of a similar of fence earlier has no bearing on the next one, except just as a side note which Court will most probably reject. A new case has to stand on its own merits.

indeed in your case Court may well probe your reasons since you pretty much knowingly took the risk on yourself !!

Having prosecuted a person for not paying, you have given a loan again to him. Why! Its quite strange.

OK coming to your present details. Send a detailed letter to the Head of the Department by Registered Post with a copy to the Minister in charge, with a copy marked to CVC. It may work.

Once bitten twice shy, nothing more to add.

It is your duty to find out his address.  It is very easy to find out the address of the central govt service where he is working.  Even if you type in justdial or google, you can find the address of his employer.  You can file an application under RTI act to know about the details (including his position) of that person by giving his name, age etc.  And also follow the advise of sivaramprasad.

The aspect of once he is convicted will have no bearing in civil case, but it is definitely have bad remark and his period of conviction can be increased. 

You being a money lender should be having good source to hire an advocate to get his paid services, because you have clearly mentioned that the same accused was convicted earlier through a case prosecuted by you 6 years back but what prompted you to grant him a fresh loan 3 years back?  A legal notice sent to his office address will be properly served, so there is no fuzz about it, do not try to cash the wrong issues using free services of this forum.