Security has been tightened at the residence of Justice Dipak Misra, who headed the Supreme Court's three-judge bench that rejected Yakub Memon's last mercy plea on the day of his execution, after he received a death threat in writing.
Justice Misra has received an anonymous letter, which reads, "Irrespective of the protection you may avail, we will eliminate you," NDTV reported.
The Delhi Police has registered a case and is investigating the source of the letter.
Fearing probable threat from Yakub's elder brother Tiger Memon, who was the mastermind of the 1993 Mumbai blasts, security was beefed up outside the houses of the three judges on 30 July, when Yakub was hanged to death at Nagpur Central Jail.
The three judges, Misra, Amitav Roy and Prafulla Pant, had rejected Yakub's last mercy petition just a couple of hours before his hanging.
In 2006, a TADA court in Mumbai convicted Yakub, a chartered accountant by profession, of financing the 13 serial blasts in Mumbai on 12 March, 1993. At least 257 people were killed and thousands of others were injured in the blasts. He was sentenced to death in July 2007.
Dawood Ibrahim's close aide Chhota Shakeel called The Times of India and threatened of avenging an "innocent" man's "legal murder".