Military prosecutors have charged four people in the attack that burned one-fifth of activist Andrie Yunus’s body.

A trial has opened in a military court in Jakarta for four Indonesian soldiers accused of carrying out an acid attack on an activist who campaigned against the expansion of the role of the armed forces in government.

Military prosecutors charged the group, including Edi Sudarko, Budi Hariyanto Widhi Cahyono, Nandala Dwi Prasetia and Sami Lakka, on Wednesday with serious meditated assault, which carries a maximum sentence of 12 years under Indonesia’s criminal code.

The defendants, who were represented by military-appointed lawyers, appeared in court in fatigues. A defence lawyer for the men told the court they would not dispute the indictment, allowing the trial to proceed.

The attack unfolded on March 12, when activist Andrie Yunus – a ‌deputy coordinator with the Commission for Missing Persons and Victims of Violence (KontraS) – was riding a motorbike in Jakarta. Two men on another motorbike doused him with acid.

Andrie, 27, received burns across more than 20 percent of his face and body and was blinded in one eye, according to military prosecutor Mohammad Iswadi.

Although police at first identified two other suspects based on CCTV footage, four others were ultimately arrested.

They all worked for the Indonesian military’s Strategic Intelligence Agency, whose chief has since resigned, though a reason was not provided.

Iswadi said the group was angered over Andrie’s activism, but was not working on official orders.

At the time of the attack, Andrie had just finished recording a podcast, criticising what he describes as the militarisation of the Indonesian government under President Prabowo Subianto, a former general.

He had also protested an amendment ratified by Indonesia’s parliament last year, allowing active-duty military personnel to be appointed to a wider range of government posts, including in the attorney general’s office, national disaster mitigation and the counterterrorism agency.

Rights groups criticised the move as boosting military involvement in public affairs, potentially leading to abuses of power and human rights.

“The suspects deemed Andrie Yunus to have insulted and stomped on the military as an institution,” Iswadi said.

The Indonesian human rights watchdog, Komnas HAM, has separately claimed that at least 14 people were linked to the attack.

The incident “could lead to fear among civilians to criticise government officials”, the group warned.

According to Iswadi, the four men planned the attack at their military lodgings in Jakarta.

One of them obtained “rust removal fluid” from a military workshop and mixed it with battery fluid, he said, before the group went searching for Andrie on motorbikes.

The next hearing is scheduled for May 6, when the prosecution is expected to produce witnesses.