I can understand your rage, if this happened to my sister, I would personally beat that fucker to death mercilessly in front of his relatives, but sadly OP's sister is alone and we don't about OP's connections, hiring hitman is not an viable option, where are you supposed to hire them? This isn't U.S, they aren't available on dark web, even if he manages to hire one what are the odds that the hired person is not an undercover cop or someone close to the goon? Police aren't trustworthy as someone in the force would tip off the goon, best thing OP's sister can do is to contact women's helpline and stay at her friend's house while things get sorted out.