Mob killed thief and father is a suspect under section 302 IPC.

Respected sir.. on aug 2017 at around 2am we heard some noise in our neighborhood my father along with me went out.. and on the road a theif was caught many people were there and all of them were beating him.. at that moment my father called the police.. but they didn't came.. and in the same time the mob of public became huge and started beating the theif and ultimately the theif was no more... and after 2hrs the police came and took away the dead body... now the uncle of the victim filled a FIR to our locality and the police(becaise they didnt came in time)and the PS was only 1km from our locality...so the police are now harssing my father after two months of the incident..now they are saying to name the ones who killed the theif sir pls tell how to recognised them all as it was dark and many were there...the police gave notive and theartend my father to come at ps or else they have many ways..they gave two notice..but my father didnt went..if we go then will surely arrest my fathe