Marriage by fraud

My brother got married on 12th march, 2016. In the next 2 days our family observed some unnatural behavior in the girl and she didn't seem mentally sound. We called her parents home and they confessed in an hour long discussion that she is suffering from schizophrenia and they hid this fact throughout. They took their daughter home on 15th march, 2016. The couple had been living apart since then. The girl and her family did try to come announce at our doorstep and by force tried to leave their daughter at home. We registered a police report since they threatened us with some grave consequences. We filed a legal case of fraud and wanted to annul the marriage. There had been 7 hearings and the other party never appeared in the court. The case had been dragging on and we don't see it headed towards anywhere. There had been no contact between both the parties since the case got registered. No phone calls, no meetings, nothing at all. They don't show up in court as well. What to do now? We are totally confused with no clarity. The lawyer we hired doesn't seem to make any headways till now. Please guide us. It has been almost 2 years and we seek a quick remedy now.