104. Whoever, being under sentence of imprisonment for life, commits murder, shall be punished with death or with imprisonment for life, which shall mean the remainder of that person’s natural life.
Bharatiya Nyaya Sanhita, 2023
Section 104: Punishment for murder by life-convict
Chapter VI — Of Offences Affecting the Human Body
Source: official text of the Bharatiya Nyaya Sanhita, 2023 (Ministry of Home Affairs).