False fir filed by a police officer

In my native one of neighborhood attempted for half murder , and they got escaped and one day police officers came and taken my brother for Enquiry why because they are unable to find the victim but the police officers are got more pressurized from higher officers regarding this case , after taking my brother to station our parents went and asked the reason they said just Enquiry we will send him back like that they said and they not even allow us to the inside of the police station , the officers itself acts like a rowdies , after one day they sent my brother along with 3 more people to JC , after consulting lawyer , the police officers filed different case against them , (robbery case ) , while sending they taken our parent sign forcefully without giving time to read , that time they said your son is having phone contact thats why we are filing case against him like that but there is no evidence for that , can you please guide anyone how to handle this case against police ,