Thailand’s Department of Special Investigation (DSI) has concluded that Reuters cameraman Hiro Muramoto, who was killed during political protests last year, was not shot by security forces, the head of the DSI said on Sunday.

That conclusion contradicts a preliminary finding in a DSI report leaked to Reuters in December, which indicated the bullet that killed the Japanese journalist on April 10 came from the direction of troops.

DSI Director-General Tharit Pengdith said the bullet came from an AK-47, which did not match the weapon used by soldiers in the street in Bangkok that day.

“Now we know for sure the bullet that killed him was a Russian-made AK-47, which we do not have for military use,” Tharit told Reuters, adding there would be a news conference on Monday to outline the findings.

Muramoto, 43, was based in Tokyo and had come to Bangkok to help cover anti-government “red shirt” protests that lasted from March to mid-May last year. He was among 91 civilians and members of the security forces killed during the unrest.

Army spokesman Sansern Kaewkamnerd was not immediately available for comment.

He was quoted in Sunday’s Bangkok Post as saying soldiers did not use AK-47 rifles on the day in question.

However, the daily also reported “claims that the army chief of staff paid the DSI head a visit to complain about an initial department finding” that blamed soldiers for the journalist’s death.

“The DSI is likely to face questions about why it changed its stance,” it said. It added that Tharit had denied meeting the army chief of staff.

The Bangkok Post also quoted an unnamed army source as saying the army had imported about 20,000 AK-47 rifles into the country two decades ago. “About 19,000 of them had been distributed for use at military camps nationwide, while the rest were kept at the army’s weapon storage site,” it said.