United Front for Democracy against Dictatorship (UDD) chairman Jatuporn Prompan on Thursday submitted an open letter to Pol Gen Somyos Pumpanmuang, the police chief-designate, asking that investigators strictly work within the law in handling cases against the alleged "men in black".
The suspects are alleged to have used illegal war weapons and been involved in violence causing death and injury during the 2010 political violence.
Mr Jatuporn said the letter asked that police investigators ensure fairness and transparency in their handling of the cases.
Mr Jatuporn was accompanied by Tida Thawornseth, a former UDD chair, her husband Weng Tojirakarn and a team of lawyers at his meeting with Pol Gen Somyos.
In the letter, the UDD said the information initially released by police at a press conference on the arrest of five "men in black" led the public to understand that the suspects had caused the death of Gen Romklao Thuwatham (then a colonel) and other soldiers during a clash between the military and red-shirt protesters at Khok Wua intersection on April 10, 2010.
Red-shirt leader Jatuporn Prompan wants police to work within the law in handling cases against the alleged "men in black". (Bangkok Post photos)
In fact, the police had only charged them with illegally having war weapons in their possession and carrying them in public without a permit.
It had been found, with supporting evidence in a separate investigation, that Gen Romklao and four other soldiers were killed by the explosions of M67 grenades, not with the weapons mentioned in the press conference, according to the UDD letter.
The letter alleged the bodies of soldiers killed in the political violence had not undergone a proper post-mortem examination as required by the Criminal Procedures Code, except for Pvt Narongrit Sala.
The press conference was intended to led the public to believe the political violence in 2010 and 2014 was linked, without giving credible evidence and information, according to the letter.
The UDD letter asked Pol Gen Somyos to allow the Department of Special Investigation (DSI) to handle all of the cases on the deaths of both soldiers and civilians in 2010. The investigation should be carried out quickly and properly in line with the legal procedures to prevent innocent people from being accused.
There should not be any violation of human rights or acts of intimidation to force confession. Moreover, all press conferences on arrests of suspects should result from clear evidence, and not be called for the political interest of any individuals or groups, the letter said.
The letter said the UDD rejected any conclusions which could lead the public to believe the UDD had an armed force. The movement's past activities had been carried out in a peaceful manner, according to the letter.