Jailed gangster Lawrence Bishnoi was brought to Delhi's Mandoli Prison from a Gujarat jail in the early hours of Thursday, officials said.
A senior jail official said Bishnoi has been lodged in the Mandoli jail due to security reasons.
On May 2, jailed gangster Tillu Tajpuriya was stabbed to death with improvised weapons allegedly by four members of the Gogi gang inside the high-security prison.
Last month, the Gujarat Anti-Terrorist Squad (ATS) got Bishnoi's custody in connection with a case of cross-border smuggling of drugs.
The ATS wanted to question the gangster about his possible links in connection with the seizure of 40 kg heroin worth more than Rs 200 crore from a Pakistani fishing boat in the Arabian Sea off the Gujarat coast in September last year.
The Delhi Police Special Cell has also arrested an alleged member of the Bishnoi gang after a brief encounter near the Britannia Chowk flyover here on Monday.
The accused, identified as Yogesh alias Himanshu, was at large for three years after jumping interim bail in a murder attempt case in Delhi, they said.