What is a zero FIR?

An FIR that can be filed at any police station irrespective of the place of crime and area of jurisdiction is referred to as a Zero FIR.  

The police cannot refuse to file an FIR. 

Once you register they are also urged to conduct a prelude investigation despite lack of jurisdiction. This is done in order to ensure that the evidence in certain cases involving offences of Sexual abuse is collected at the right time and isn’t lost. 

They are bound to register the FIR (this is called a zero FIR) and forward it to the concerned police station for further action.