Fir against Husband

Hi Sir, My sister in law get married to family who demanded dowry from day one and they start complaining about girl from day one. Also not even a family member of groom has shared anything online or offline and even boy has not shared his mairrage details with company. Husband use to lock her in house and even not take away with her for anything in his 4 months of tenure. after many push he only gone for once with her out but his family pressure and his behavior was suspicious from day one. when the things was not bearable so girl also wanted to go home but when we mate with their family they forsen us to take the girl with us for few months. but they never call and whenever we call to call girl he always give us excuse for training and etc. one the completion of one year boy has called the girl and said we can't call you at my home even his rented accommodation he has left and shifted with his brother in different location. also he has not called the girl in his family function and staying with his brother. these days boy is out of india. Sir, girl has complaint about this in CAW cell but he has never responded to police phone also his father has mention that he has not attachment with his son. his relatives are keep asking for another date and always come up with silly excuses. Finally complaint converted in FIR but still no one from groom side has even turn up and even some body come they only said we don't know and donot have any connection with family. Please suggest what should i do now? boy is out of india and he even don't visit his native home town and we don't know his current location. Please suggest for next step??