Five policemen convicted of murdering a 17-year-old man from Kalasin were released on bail Tuesday by the Criminal Court.
A key witness, the teenage victim's aunt, said she would seek to extend her enrolment in a witness protection programme now that the convicted killers have been set free.
Pikul Prohmchan, one of three key witnesses in the murder case, said she would petition the Department of the Special Investigation (DSI) because the release of the five convicts - three of whom were sentenced to death - could put her life in jeopardy. "I'm afraid that we might be killed before the convicts receive the capital punishment," she said.
Kiattisak Thitboonkrong, the 17-year-old murder victim, was Ms Pikul's nephew. She and two other witnesses were placed under the DSI's witness protection programme when the agency began investigating the murder.
The programme expired on Monday when the the court convicted the five policemen for the killing.
Six police officers from Kalasin's Muang district police station were charged in connection with Kiattisak's July 2004 murder.
The teenager had been arrested for alleged motorcycle theft and was found hanging from the ceiling of a hut in Roi Et's Chang Han district several days after being released from Muang Kalasin police station.
Angkhan Khammoonna, Sutthinan Nonthing, and Phansin Uppanan - all holding the rank of senior sergeant major - were sentenced to death for premeditated murder and hiding a corpse.
Pol Lt Col Sumit Nunsathit was sentenced to life imprisonment for premeditated murder, while Pol Col Montri Boonlue was sentenced to seven years in jail for abuse of authority to help protect his subordinates from prosecution.
The sixth defendant, Pol Lt-Col Samphao Indee, was acquitted.
Pol Col Montri was chief of the police station, Pol Lt Col Sumit was his deputy and Pol Lt-Col Samphao was chief investigative officer at the time of the crime.
The three sergeants sentenced to death were their subordinates.
Ms Pikul said one of the witnesses - Surasak Poonklang - had been killed in an accident late in 2009 before being able to testify in court. "Who knows if this will not happen to us, too."
DSI investigator Piyawat Kingkate said Tuesday there are another 20 teenagers who were killed in Kalasin province and whose deaths were believed to be linked to alleged extra-judicial killings during the Thaksin Shinawatra government's war on drugs between 2003-2005. They comprise 17 men and three women.
Of these, the DSI has taken up seven or eight cases for investigation, Pol Col Piyawat said.
The cases share similar circumstances with Kiattisak's case but the DSI had to call off the investigation because investigators could not identify the murder suspects. Relatives of the victims have expressed fears of retribution if they came forward as witnesses, and have refused to testify, Pol Col Piyawat said.