A lower court had on May 30 let off Kumar in the 29-year-old case saying he deserved the 'benefit of doubt' as key witness Jagdish Kaur did not name him as an accused in her statement given to the Justice Ranganath Mishra panel in 1985.
'It was a matter of fact that when eye witness and complainant Jagdish Kaur had submitted her affidavit before Justice Ranganath Mishra Commission in 1985, she had not mentioned the name of Sajjan Kumar in any manner though the other accused had been named,' it had said.
The lower court, however, had held five others guilty in the case and awarded varying jail terms for being part of the mob that killed the Sikhs.
While ex-councillor Balwan Khokkar, Girdhari Lal and retired naval officer Captain Bhagmal were given life term, rest two former MLA Mahender Yadav and Kishan Khokkar were given three years jail term for their lesser roles.
The probe agency, in its appeal to the High Court, has said the trial court erred in acquitting Sajjan Kumar as it was he who had instigated the mob during the riots that broke out after the assassination of then Prime Minister Indira Gandhi on October 31, 1984.
Kumar, a former Lok Sabha MP from Outer Delhi, and five others were tried in the case dealing with the killing of five Sikhs Kehar Singh, Gurpreet Singh, Raghuvender Singh, Narender Pal Singh and Kuldeep Singh who were members of the same family, by a mob in Delhi Cantonment's Raj Nagar area.
The case against Kumar and others was registered in 2005 on a recommendation by Justice G T Nanavati Commission. CBI had filed two charge sheets against him and the other accused in January 2010.