The government should declassify all documents related to the mysterious death of former Prime Minister Lal Bahadur Shastri to “clear the air once and for all”, his son Anil Shastri said on Friday.

The freedom fighter had died in Tashkent in January 1966 soon after he signed the Tashkent Pact, a peace accord with Pakistan. The family has challenged the official version that he died of a cardiac arrest.

“We want all documents pertaining to Shastriji’s death to be declassified,” Anil Shastri said in Chandigarh, according to PTI. The Congress leader was speaking on the sidelines of the release of the Punjabi translation of the book Lal Bahadur Shastri: Lessons in Leadership.

“Many things have been said about the way he died, even yesterday a young man walked to me at Delhi airport and asked me how my father had died,” he said. “Family members and common public still have suspicion because the circumstances in which Shastriji died were uncommon.”

He said that the findings of the Raj Narain Committee, which looked into the death, should also be made public.

“When BJP [Bharatiya Janata Party] was in opposition, one of their major demands was that the documents related to Shastriji’s death be declassified,” he said. “Today, I am not asking as a politician, but as a son.”

He said he had written a letter to Prime Minister Narendra Modi on the matter a year back, but he had not got a reply yet.