The warder, Joginder, was supposed to be on duty till 10 PM but he allegedly left around 9.55 PM, without waiting for the other warder to come and officially relieve him for the day as per protocol.
"The warder was suspended on Thursday (August 13)," said Mukesh Prasad, DIG (Prisons) Tihar.
The prison authorities have initiated an inquiry into the incident to figure out suspected loopholes in security inside the jail premises. A report based on this enquiry is yet to be prepared, said Prasad.
The deceased, identified as Dipak, was allegedly beaten up with iron rods sourced from a window and then stabbed with a sharp object, said a police official.
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He was rushed to Deen Dayal Upadhyay hospital, where he succumbed to his injuries around 11.30 PM. A case of murder was then registered at Hari Nagar police station in west Delhi, said the official.
The accused were identified as Satpal Bedi, Manpreet Singh, Riyaz and Suraj.
Dipak was lodged in Tihar since 2008 in several cases ranging from dacoity to attempt to murder, the official added.