The Thai army has denied claims that up to 40 people are still unaccounted for following a protest in southern Thailand which led to 85 deaths.
The authorities' treatment of protesters incensed the region
The Bangkok Post said relatives of the people alleged to be missing had formally petitioned the authorities.
But General Sirichai Thanyasiri, head of the military in southern Thailand, said it was impossible that more people were still unaccounted for.
The dispute came as apparent revenge attacks for the deaths continued.
Police said a second Buddhist man had been found beheaded, in Narathiwat province, with notes beside him indicating he was killed in revenge for the deaths two weeks ago.
The latest violence started following a protest in the town of Takbai, Narathiwat province, on 25 October. The army said 85 people died in the aftermath, 78 of them after they were overcrowded into army trucks following their arrest.
General Sirichai denied rumours that the death toll could be higher.
Home to most of Thailand's 4% Muslim minority
Muslim rebels fought the government up to the mid-80s
Suspected militants have upped attacks this year, targeting Buddhists
Security forces' response criticised by rights groups
But the rumours have stoked memories of a 1992 incident known as Black May, when pro-democracy students in Bangkok disappeared after an army crackdown.
In the wake of the Takbai protests, 22 bodies remain unidentified.
Army spokesman Colonel Somkuan Saengpattranet told the BBC that DNA samples had been taken from these bodies, and they did not correspond to the 40 people now being reported missing.
He confirmed that an investigation has been launched and that it would be carried out by the police and local authorities.
Authorities say reprisal attacks for the Takbai deaths by suspected Muslim militants have killed at least 20 state officials and Buddhist civilians.
Police on Tuesday said the beheaded corpse of a 60-year-old rubber tapper was found accompanied by several notes, one of which read: "This is trivial compared to the killings of the innocents at Takbai."
The beheading is the second such killing in a week. The remains of a Buddhist village leader were found in Narathiwat province on 2 November.
Earlier on Tuesday a Buddhist couple was killed by a gunman riding on a motorbike in nearby Yala province.
Thai Prime Minister Thaksin Shinawatra has admitted that mistakes were made when the security forces broke up the demonstration, but has so far refused to apologise.
Thailand's Muslim population has long complained of discrimination by the authorities in Bangkok.
But the security situation has been deteriorating since the start of this year, with almost daily attacks which the authorities have blamed on Muslim separatists.