New Delhi: A 42-year-old Central Industrial Security Force (CISF) constable was beaten to death by a former Delhi Police constable and his friend when he stopped them from entering the premises of a CISF residential colony, police said Monday. The incident took place around 10:45 p.m. Sunday in Bawana area of Delhi. The victim, Jaiveer Singh, was rushed to a nearby hospital where doctors declared him dead due to severe head injury.