A Thai court on Thursday dismissed murder charges against former premier Abhisit Vejjajiva and his ex-deputy over a bloody 2010 protest crackdown, months after a military coup tipped the balance of power in the politically divided nation.
Relatives of the victims criticised the surprise decision to drop the case as politically motivated. The charges were brought to court under a previous government led by Abhisit's rivals who have since been ousted from office.
Scores of demonstrators died under Abhisit's establishment-backed leadership in street clashes between mostly unarmed "Red Shirt" supporters of fugitive former premier Thaksin Shinawatra and security forces firing live rounds in Bangkok.
A criminal court in the capital, which previously agreed to hear the charges, ruled that it did not have jurisdiction in the case against Abhisit and his then-deputy Suthep Thaugsuban because they were holders of public office at the time and acting under an emergency decree.
It said the only court with the authority to consider the allegations was the Supreme Court's Criminal Division for Holders of Political Positions.
The ruling comes three months after the military seized power from Abhisit's political opponents in a bloodless coup.
Army chief General Prayut Chan-O-Cha, who was last week picked as prime minister of the Southeast Asian nation by a junta-appointed legislature, is often described as the architect of the 2010 crackdown.
"It's 100 percent about politics -- soldiers are among those accused," said Phayaw Akkahad, the mother of a nurse who was shot dead in the grounds of a Buddhist temple while treating injured during the crackdown.
"My daughter was murdered. A woman like me will not give up," she added.
In August 2013 a court inquest found that soldiers had used "high velocity machine gun" fire to target victims including Phayaw's daughter.
No member of the armed forces has been prosecuted in connection with the deaths.
Critics accuse Thailand's courts of being politically influenced, particularly in favour of the Bangkok-based elite.
Prosecutors had accused Abhisit and Suthep of issuing orders that resulted in murder and attempted murder by the security forces.
Both suspects denied the charges.
Chokchai Angkaew, a lawyer for the plaintiffs, who include relatives of the victims, said they planned to appeal against the dismissal, adding: "It's not over."
The country's National Anti-Corruption Commission is now expected to consider whether the pair abused their power with the crackdown.
If it believes there is sufficient grounds, the panel can forward the case to the attorney general for possible submission to the Supreme Court's Criminal Division for Holders of Political Positions.
Suthep, who went on to lead months of street protests against Abhisit's successor Yingluck Shinawatra, appeared in court sporting a shaven head and the orange robes of a Buddhist monk after entering the clergy.
Abhisit meanwhile was seen smiling in court after the ruling.
Thailand's long-running political conflict broadly pits a Bangkok-based middle class and royalist elite, backed by parts of the military and judiciary, against rural and working-class voters loyal to Thaksin.
Thaksin, a billionaire tycoon turned premier, was toppled in a coup in 2006 and lives in self-exile to avoid prison for a corruption conviction.
Yingluck, his younger sister, was removed from office in a controversial court ruling in May this year, shortly before the military seized power.
Since taking over the junta has abrogated the constitution, curtailed civil liberties under martial law and summoned hundreds of opponents, activists and academics for questioning.
The military rulers say they want to reform Thailand to end years of political turbulence and street violence, but critics see the takeover as an attempt to wipe out Thaksin's influence.
In the 2010 protests, the Red Shirts were demanding snap elections, saying Abhisit's government took office undemocratically in 2008 through a parliamentary vote after a court stripped Thaksin's allies of power.
Tens of thousands of demonstrators occupied parts of central Bangkok for weeks before the army ended the standoff.