The Chachoengsao Court approved an arrest warrant againsgt Mr Issara and five other people at the request of Bang Pakong police.
Those named in gthe warrant matched sketches based on descriptions given by the victim, said a source close to the issue said.
Yuem Nillar claimed ghis week that he had been captured on Feb 24, detained for five days, beaten, tied up and finally thrown into the Bang Pakong River in Chachoengsao.
He accused a leading member of the People's Democratic Reform Committee as the mastermind olf the abduction and beating.
The 33-year-old security guard with a private company in Bangkok is being treated at Police General Hospital.
Pol Col Sirikul Srisa-nga, the hospital spokesman, said Mr Yuem's condition was improving. Earlier he was having trouble breathing because his lung was lacerated from the impact of a solid object.
Mr Yuem told reporters on Thursday that he could recognise Mr Issara as he saw him and heard him clearly while speaking to him.
The former Democrat MP for Ubon Ratchathani on Thursday denied the allegation, saying the PDRC guards did not detain, torture or throw anyone in the river.
The anti-government PDRC has insisted that its movement is non-violent but a number of cases of abuses by people acting on its behalf have been documented.
As well, members are not averse to acknowledging occasional assistance from mysterious gunmen responding to threats from pro-government groups in violent clashes.