By Ambika Ahuja
BANGKOK (Reuters) - Thai police said on Thursday they had no evidence to indicate troops killed Reuters cameraman Hiro Muramoto last year, backing a recent reversal of preliminary findings that a soldier may have fired the fatal bullet.
After reviewing a report by Thailand's Department of Special Investigation (DSI), police said they could not determine whether Muramoto, a 43-year-old Japanese national, was killed by troops while filming anti-government demonstrations last April.
The DSI had said last November that a soldier may have fired the shot, but now says the type of bullet was inconsistent with those used by soldiers that day.
The latest police investigation concurred with the DSI.
"Based on what we have received (from the DSI), there is not yet any conclusive evidence or witness accounts to show that the authorities were responsible," said Police General Ek Angsananond.
"We have sent the report back to the DSI, which will continue with the investigation. If they find more and want us to look at it again, we will do so."
Muramoto was killed by a high-velocity bullet wound to the chest while covering clashes between "red shirt" protesters and troops in Bangkok's old quarter on April 10. He was among 25 people, mostly protesters, who died that night.
Mysterious gunmen clad in black were mingling with the protesters and firing at troops.
Witness accounts in a preliminary DSI investigation seen by Reuters in December said the fatal shot came from the direction of troops. A witness was quoted as saying he saw "a flash from a gun barrel of a soldier", then watched Muramoto fall after he was shot in the chest while filming the troops.
DSI Chief Tharit Pengdith has said investigators had not been able to determine who fired the shot that killed Muramoto. However, he said on Thursday that the police investigation had showed that soldiers were not responsible.
"We will continue with the investigation. But at this level, it's clear from the police investigation that members of the security forces were not involved," he said.
Reuters News Editor-in-Chief Stephen J. Adler said the inconclusive findings made full transparency about the investigation process all the more imperative.
"We call on the Thai government and all the relevant authorities to conduct a thorough, considered, objective and transparent investigation of his killing," Adler said in a statement. "Muramoto-san's family and Reuters colleagues deserve to know how this tragedy occurred and who was behind it."
A report last month by the Bangkok Post newspaper said the DSI chief had been paid a visit by the army chief of staff "to complain about an initial department finding" that blamed soldiers for the journalist's death.
The latest comment by the police is likely to reopen the debate over how exactly Muramoto was killed and the identity of the masked gunmen seen moving among the demonstrators or firing from above on the night he died.
Jatuporn Prompan, a red shirt leader and opposition lawmaker, said the investigation had been interfered with to absolve the powerful and politically influential army of any responsibility.
"This is a staged drama to fool the public, to fool the Japanese," he told Reuters.
"When the DSI concluded its preliminary investigation, it could not find a way out of that, so it sent it to the police to give them room for alteration."
The government says the shadowy gunmen were "terrorists" allied with the red shirts and it has blamed them for most of the deaths during the clashes.
The military has denied responsibility for any of the 91 deaths during the violence in April and May, a claim most independent observers say is implausible.
DSI's Tharit said investigators would now focus their investigation on the red shirts and "black-clad men" rather than the soldiers.
He also said that if the case was not solved within a year from now, the DSI would consider sending its findings to prosecutors to suspend the investigation until new evidence or witnesses were available.
Prime Minister Abhisit Vejjajiva said the case would not be forgotten.
"The case won't go cold because everyone is watching it," he told reporters. "But a criticism when the process is ongoing would only cause more confusion. We have to give investigators a chance to do their best."
(Additional Reporting by Chalathip Thirasoonthrakul; Writing by Martin Petty; Editing by Jonathan Thatcher)