The police probe into the attack on college lecturer T J Joseph, 52, is yet to make much headway although enough hints have come about the meticulous planning and execution of the crime.

A day after two activists of the Popular Front of India (PFI) were arrested, an officer in the probe team got a threatening call from a district functionary of the outfit.

Several district-level PFI leaders have gone into hiding following raids at the organisation’s strongholds in the rural areas of Ernakulam. The call to the circle inspector was tracked down to Rasheed, a district PFI leader.

Joseph was on Sunday attacked by some unidentified men who chopped off his right hand, at Muvattupuzha in central Kerala . The lecturer had sparked off a controversy four months ago for reportedly insulting Prophet Muhammed in a question paper. The PFI has justified the attack on the lecturer for hurting the sentiments of the community.