According to information accessed under the Right to Information Act, CBI said it was still awaiting the certificate of Prabhakaran's death from the authorities in that country.
Rajiv Gandhi was assassinated in Sriperumbudur in Tamil Nadu on May 21, 1991 during an election rally.
"The matter is regularly being pursued through the diplomatic channel," B N Mishra, Superintendent of Police at the Multi Disciplinary Monitoring Agency (MDMA) said in reply to an RTI query.
"CBI has taken up the matter with authorities concerned in Sri Lanka through diplomatic channels for supplying authenticated copy of his death certificate, which is still awaited," the reply read.
The CBI said, "Both the governments are regularly in touch with each other for expediting enquiries into certain aspects of the case pending with the Government of Sri Lanka."