In his complaint to the police, Agrawal said that the letter was received at his office here in south-east Delhi's Jangpura Extension on August 31 when he was at Rae Bareli attending a public function. He opened the letter on September 2 and reported the matter to the police.
An FIR has been registered under Sections 506/507 (criminal intimidation) of IPC, said a police officer.
Agrawal, who is also a senior lawyer at the Supreme Court, has claimed that the letter was sent by a person who represents a community and allegedly threatened to kill him (Agrawal) for any sort of intervention in their pursuits.
"Investigation of the case is underway," the police officer added.