Jakarta – Indonesia's justice system failed in overturning the conviction of a pilot for the murder of a leading rights activist, Human Rights Watch said, calling for a new investigation.

The Supreme Court this week abolished a 14-year sentence for Pollycarpus Priyanto for the arsenic poisoning of prominent campaigner Munir on a flight to Amsterdam in 2004. He has been the only person convicted in the case.

Evidence presented during the trial showed he had links to Indonesia's powerful intelligence agency (BIN), which stonewalled a presidential fact-finding team tasked with investigating the murder.

"The failure to secure a conviction for Munir's murder is a huge blow for human rights protection and the reform process supposedly underway in Indonesia," Brad Adams, the rights group's Asia director, said in a statement. "This was a test case for the Indonesian justice system. It has failed."

The rights watchdog called on the court – which held a closed-door session and is not compelled to explain its verdict – to publish its decision. "The evidence against Pollycarpus was overwhelming, as reflected in the evidence presented in the earlier court decisions and the report of the president's own fact-finding team," said Adams.

HRW also called on the government to publish the final report and recommendations of the presidential fact-finding team set up at the end of 2004 to investigate the murder.

"President Susilo Bambang Yudhoyono should also establish an independent body to audit the police investigation and Attorney General's response to Munir's murder," the group said.

"The police and the attorney general's office have steadfastly continued to ignore evidence and recommendations submitted to them by the presidential fact-finding team, which also implicated senior intelligence officers and airline officials in involvement in the murder," said Adams. "The truth needs to be uncovered, including who ordered and planned the killing, no matter where the trail leads."

Munir, who was 38 years old, had made numerous enemies through his work during and after the rule of dictator Suharto, which ended in 1998. Judges had said Priyanto's motive was to protect the military and BIN.