The letter, which was purportedly sent by the Jammu and Kashmir unit of ISIS, was delivered to Bitta's residence on Talkatora Road here, following which the matter was reported at the North Avenue police station on Monday, a police officer said today.
On the basis of the complaint, the police registered an FIR yesterday under sections 506 and 507 (criminal intimidation) of IPC and took up investigation, he said.
Bitta's personal secretary, who filed the complaint, told police that apart from Bitta, Vinod Bhardwaj, national general secretary of the front, and other members have also been threatened by in the letter.