Advocate A P Singh, who represents accused Akshay Thakur and Vinay Sharma, has also sought a high-level enquiry into the incident.
He has annexed a letter, the contents of which were incoherent, purportedly giving the threat to him and the court among others.
Additional Sessions Judge Yogesh Khanna directed the investigating officer (IO) of the case to look in to matter. ""Let local police also investigate the matter," the judge said.