The nation is observing the Jail Killing Day on Thursday. The day is remembered as one of the most tragic events in the history of the country, which has emerged as an independent state after a long bloody war against Pakistan.Four national leaders - Syed Nazrul Islam, Tajuddin Ahmed, M Mansur Ali and AHM Qamruzzaman - were killed by a cabal of disgruntled army officers, just 79 days after the August 15 massacre of Bangabandhu Sheikh Mujibur Rahman and most of his family members.On this occasion, President Abdul Hamid and Prime Minister Sheikh Hasina have already issued separate messages, paying rich tributes to them for their contributions to movements for democracy and Independence.To mark the day, the ruling Awami League, its front organisations and several socio-cultural organisations have already chalked up various programmes.Commemorating the day, the jail authorities have organised a five-day exhibition at the former prison which has recently been shifted to Keraniganj.The cells, where the veteran leaders were assassinated, have been turned into museums, and their clothes and things have been preserved there.Besides the cells, the murals of the leaders were set up on the jail premises. People of all walks of life thronged there to see them. The exhibition featuring their works will continue till November 5.