The CBI on Tuesday collected voice sample of Congress leader Jagdish Tytler in connection with a 1984 case of anti-Sikh riots in the city's Pul Bangash area, officials said.
The agency, which has filed three closure reports so far, made the move after getting "fresh evidence" in the case, they said.
Tytler arrived at the Central Forensic Science Laboratory in the CGO Complex where his voice sample was collected by experts, they said.
He was allowed to leave in the forenoon after the exercise was complete, they said.
The case pertains to the riots at Gurudwara Pul Bangash in North Delhi where three people were killed on November 1, 1984, a day after the assassination of then prime minister Indira Gandhi by her Sikh bodyguards.
The victims had filed a protest petition challenging the CBI's closure reports in the case.
The court had in December 2015 directed the CBI to further investigate the matter and said it would monitor the probe every two months to ensure that no aspect is left uninvestigated.
The agency had reinvestigated the case of killing of Badal Singh, Thakur Singh and Gurcharan Singh near the Gurudwara after a court in December 2007 refused to accept its closure report.
The CBI is also regularly filing its status reports in the matter before a special court here.
