Chandigarh, July 15 -- Three months after two unidentified men hurled a grenade outside the Punjab BJP headquarters in Sector 37, Chandigarh, police have filed a 1,465-page chargesheet, naming 56 prosecution witnesses, including two protected witnesses whose identities have been concealed for security reasons. The chargesheet also reveals the use of gait analysis - the study of a person's movements while walking, including stride, abnormalities etc - for the first time by Chandigarh police. The crude bomb was hurled at the party office on April 1 but luckily, there were no casualties. It did, however, damage a parked scooter, shatter the windowpanes of a nearby car and leave splinter marks on the boundary wall. The National Investigation Agency (NIA) also joined the probe after the incident, while Babbar Khalsa International (BKI) claimed responsibility for the attack. An FIR under Explosives Act and Unlawful activities (Prevention) Act was registered. According to the prosecution, police have named 11 accused in the case. Nine have been arrested, while the alleged foreign-based conspirators Harpreet Singh alias Happy Passian and Babbar Khalsa International operative Surjit Singh alias Jota remain absconding. Two accused, Gurtej Singh and Amanpreet Singh, were arrested from Rewari. The investigators took the duo to the spot and asked them to recreate the scene, including throwing a grenade, fleeing the spot, and speaking while running and crossing the road. This was compared with the videos and closed-circuit television (CCTV) camera footage that emerged after the incident. The recordings have been sent to the Central Forensic Science Laboratory (CFSL), Chandigarh, for comparison. The investigation also relied on financial and digital evidence. Police analysed bank transactions to trace the alleged movement of funds linked to the conspiracy and examined mobile phone location data to establish the movements and roles of the accused. The chargesheet further states that the alleged escape route after the attack was reconstructed using Google Maps. The prosecution has also detailed the alleged conspiracy behind the attack, outlining how different accused allegedly received, stored and transported the grenade and other weapons before they reached the two alleged attackers....