How dose investigation carried out in 498a case on nri

Any Indian wife and her relative can file 498a on her husband, his parents, sisters, brothers, grandparents, uncles, aunts, cousins, wives of brothers, and other relatives. 498a (dowry harassment case) leads to arrest without any verification or investigation. 

A. Safeguard yourself, your parents and your relatives.

1) Be very polite in all circumstances. Record all conversations (voice, chat, email, letters, etc.) with those threatening and keep the originals in a safe place. Never produce the originals before anyone, not even before your lawyer. You can buy Olympus W-10 voice recorder, which costs about Rs.4500. You can also buy a telephone recorder.
2) Write a complaint to your nearest police station, detailing about blackmailing, her false allegations and her unscrupulous behavior. And request in your complaint to make her stop the threats and abuses immediately. 
3) File RCR (Restitution of Conjugal Rights). Remember to include conditions that she should agree on before she starts living with you again. 
4) Collect evidence to prove that you have neither demanded dowry or have taken it anytime.
5) Collect evidence to prove that she moved out of the bond of marriage for no apparent reason.
6) If she does not already know, make sure that she does not come to know that any of your family members is an NRI. 
7) Don't remain home during weekends and holidays. Have proofs of where you were. For instance, if you were in a mall, have a credit card transaction in that mall and keep the copy of that transaction. 

If the offence is not occured in India, the case is not maintainable.