A bench of justices G S Sistani and G P Mittal issued notice to the CBI and Kumar for August 27.
The notice was issued on a plea filed by members of the victims' family who contended that the trial court had failed to appreciate the legally admissible evidence in its verdict.
The appeal filed by Jagdish Kaur and Nirpreet Kaur, who had lost their close relatives in the carnage following the assassination of then prime minister Indira Gandhi, has sought setting aside of the trial court's April 30 judgment.
They have in their plea filed through advocate Kamna Vohra contended that the verdict was "erroneous" as the trial court had failed to appreciate that there was ample legally admissible evidence against Kumar to show he had allegedly "engineered" the murders of five Sikh persons in Raj Nagar area of Delhi Cantonment.
They also submitted that the trial court had ignored the statements of Jagdish Kaur, Jagsher Kaur and Nirpreet Kaur who were direct witness to Kumar's presence and "speech of hatred" given by him on November 2, 1984.
On April 30, allowing Kumar to walk free in the case, the trial court in its 129-page verdict had said that Jagdish Kaur's subsequent testimony, that she had seen him instigating a mob with his provocative speech, was "not acceptable and believable".
The court had acquitted Kumar, a former Lok Sabha MP from Outer Delhi, but convicted five others -- Balwan Khokkar, an ex-councillor, Mahender Yadav, an ex-MLA, Kishan Khokkar, Girdhari Lal and Captain Bhagmal -- for their involvement in the case.
The case relates to anti-Sikh riots that had broken out after the assassination of Indira Gandhi on October 31, 1984.
Gandhi was shot dead by two of her bodyguards, who were Sikhs, at her residence here.
The case, in which these five persons were held guilty, deals with the death of five Sikhs -- Kehar Singh, Gurpreet Singh, Raghuvender Singh, Narender Pal Singh and Kuldeep Singh -- who were members of the same family.
Kehar and Gurpreet were the husband and son respectively of complainant and eye-witness Jagdish Kaur while Raghuvender, Narender and Kuldeep were the brothers of Kaur and another witness Jagsher Singh.
The case against Kumar and others was registered in 2005 on a recommendation by Justice G T Nanavati Commission. The CBI had filed two charge sheets against him and the other accused in January 2010.
The trial court had in May 2010 framed charges against Kumar and the five others under Sections 302 (murder), 395 (dacoity), 427 (mischief to cause damage to property), 153-A (promoting enmity between different communities), 120B (criminal conspiracy) and other provisions of the IPC.
The Delhi police had earlier probed the riots case and the investigation was handed over to the CBI in 2005. The bureau had told the court there was a conspiracy of "terrifying proportion" between Kumar and the police during the riots.
The agency had said the police had kept its "eyes closed" to the widespread violence.
The CBI had also alleged that in all the complaints, wherever Kumar's name had cropped up, it was "immediately eliminated" from the Delhi police records.
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