In 1984, a fact-finding team jointly organized by People's Union for Democratic Rights (PUDR) and the People's Union for Civil Liberties (PUCL) concluded that attacks on members of the Sikh community in the 1984 anti-Sikh riots were not from spontaneous outrage over the assassination of Indian prime minister Indira Gandhi, but rather the result of deliberate planning by important politicians of the Indian National Congress party. The investigators found that the member of parliament who was most commonly named by Sikh riot survivors for being responsible for the attacks in the Delhi locality of Sultanpuri was Sajjan Kumar.
Similarly, Sikh riot survivors in the locality of Mangolpuri nearly unanimously named Kumar as having "masterminded the violence." They alleged that Kumar had given Rs. 100 and a bottle of liquor to each attacker in the riots. The investigators also observed Sikh riot survivors confront Kumar directly at the Mangolpuri police station accusing him of being responsible for the riots. Later, Kumar attempted to provide food aid to hungry Sikh survivors at a refugee camp, but the refugees refused it, saying that he was behind the riots in the first place.[5]
Prior to 2005, the Delhi Police had investigated Kumar's role in the riots. The investigation was then given to the Central Bureau of Investigation (CBI) in 2005 by recommendation from the Justice G.T. Nanavati Commission. In the subsequent investigation, the CBI concluded that there was a conspiracy of "terrifying proportion" between Kumar and the police during the riots, and that the Delhi police had systematically removed Kumar's name from all eyewitness testimony of the riots.[6]
In 2010, as a result of the CBI investigation, Kumar was tried for murder, dacoity, mischief to cause damage to property, promoting enmity between different communities, criminal conspiracy, and other provisions of the Indian Penal Code.[6] Eyewitnesses testified how Sajjan Kumar had colluded with the police and incited mobs to kill Sikhs.[7] In 2012, the CBI prosecutor told a Delhi court that riots targeting the Sikhs had the "patronage" of Sajjan Kumar.[8][9] CBI alleged that he organised anti-Sikh riots and he, along with five others, are being tried for killing six Sikhs.[10]
In April 2013, the Karkardooma district court in Delhi acquitted Sajjan Kumar, while convicting five others, leading to protests.[6] On 27 August 2013, the Delhi High Court accepted an appeal filed by the CBI against Kumar's previous acquittal by a lower court. CBI stated that the trial court "erred in acquitting Sajjan Kumar as it was he who had instigated the mob during the riots".[11]
He was sentenced to life imprisonment by the Delhi High Court on 17 December 2018 for his role in the 1984 anti-Sikh riots, being convicted for murders of five family members and burning of a gurudwara.[12] On 18 December 2018, he resigned from his party.[2] His lawyer said that they would appeal in the Supreme Court of India.[13][14]
Kumar later filed an interim bail plea on medical grounds in the Supreme Court, but it was rejected by the court on 13 May 2020 stating that he did not need to be admitted to a hospital; however, the court scheduled a hearing of his regular bail plea in July.[15] It later rejected another interim bail plea on 4 September and said he did not need to be admitted to a hospital,[16] but stated it will hear his appeal after the courts resume their regular functioning which was affected due to the COVID-19 pandemic.[17]
A special CBI court granted him bail in one case related to the 1984 riots on 27 April 2022, however he remained in jail due to his conviction in another case related to the riots.[18] The Delhi High Court however stayed his release in July 2022 after it was challenged by the Special Investigation Team investigating him.[19]
On February 12, 2025, Kumar was convicted in a second case for instigating and participating in the murder of Jaswant Singh, and his son, Tarundeep Singh. The two Sikh men were assaulted by a mob of Indian National Congress supporters on Nov 1, 1984, doused with petrol and burnt alive. Kumar and his supporters also assaulted the wife and niece of Jaswant Singh who tried to protect the two men. 14 eyewitnesses testified against Kumar for his active role in leading the assault.[20] He was given another life sentence for his role in the murders.[21]
Kumar was acquitted in one of the cases pertaining to riots, with a Delhi court ruling that there wasn't enough evidence to establish his guilt in the murders of Sohan Singh and his son-in-law Avtar Singh.[22]