My sister in trouble : her husband and in law mentally harrased

Got married in 1999 Darbhanga , Bihar ,sister's in law make a fake background to make marrage to his son he says my son is graduate and complete the computer diploma from aptech patna recently doing job ,my mother and father impressed by his speech and positively accepted this new relation because there are not any suspicious things looking behind ,all things is looking good his home is looking standared and he is a Bank employer ,he has two son -my sis husband is younger son ,he has taken 2.50,000 -/- as dowry ,after marrage my sis husband always stayed at patna he came home for 2 ,3 days only always says i have a urgent work at patna but all is fake he was leading a gang at patna,after two yrs he traped by police at patna he flee away from patna and shifted delhi where my sister is live together gradually my sister fells that he is looking Illiterate because he brings a form for his daughter for admission and says to his husband that fill it , he says to another person for filling it and more these types of incident that indicates that he is Illiterate .he has stolen all ornaments of my sister and her saving money ,he did all ileagel work and mentally and financially harassed to my sister, he always living out of home and police and another person visited for searching him ,she says to his father that these types of incident occurs here he says that's your matter i could not help you ,my sis has two daughter his fee is also pending ,his house rent is also pending ,my sister says to in law that please help me financially for his daughter fees he says nothing i can do ,now my sister want to right for her daughters ,now what can i do please suggest us. from Pankaj