Brother and sister in law troubling parents

There is massive family feud b/w my father and his son. he is only son and they have two daughters.. both are setlled Abroad for the last one and half years, or even more their son has been abusing them physically and torching mentally. They have been bearing it without much retaliations. His younger sister's marriage was arranged in Nov, in which he even clearly refused to support to provide any financial or physical support. Parents have had to arrange all the money on their own, without having any income from the businesses. They have bussiness the business capital inflow is controlled by their son. Nothing is given to parents. He has not given any money to support them what so ever. So after their daughter's marriage (tried before as well) , they wanted to sell a fraction of their property to repay loans. Their son didn't allow that to happen. He says that all of the assets belong to him, and he will not let have any rights of his parents. he stole all the property papers from house one day as well ( he doesnt stay with parents ofcourse) . how low can one go... he even tired to break his sister's marriage by sending bad messages to her in laws. So my parents approached police, but it wasn't much help at all. Left with no option.. they consulted some lawyers, and evicted their son from their property rights and made a "will" to grant properly rights to daughters. Since then he has been threatening them to kill. My parents are basically on the run and not staying at there place,as there is huge danger to their lives. He is threatening to kill them, as well as sent messages to us that when you are next time in india, he will kill daughters as well.. and all that crap. I am less concerned as we are in Outside and i hardly have to ever go to india it is very concerning for the parents They can't even stay at there place he threatens them thru relatives .. that he will get them killed once they are back in city. Basically gundagardi hai ... he has some political connections.. so he thinks he can get away with anything. Now sister in law filed case againt my parents n my husband for turturing her.. even if they both are not staying with my parents foralmost about 2 years.. Plz guide us wht could be done in this case..