Munarman, whom the police identified only by his initial, was arrested at his house in a luxury residential area of South Tangerang, Banten, on Tuesday and was brought in to the Jakarta Police headquarters for questioning.

“The arrest was related to allegations of M’s involvement in terror acts that took place recently,” Jakarta Police spokesman Sr. Comr. Ahmad Ramadhan said during a press briefing on Wednesday.

Ahmad did not specify the acts of terror in question, but during an earlier interview with KompasTV, he mentioned Munarman’s involvement in baiat (Muslim pledges of allegiance to a leader) at the Jakarta State Islamic University (UIN Jakarta), as well as in Medan, North Sumatra, and Makassar, South Sulawesi. The Makassar pledge, he claimed, was related to the Islamic State (IS).

Since the country’s last major set of terror attacks, which hit Surabaya in 2018 and killed dozens of people, a number of smaller, scattered attacks have occurred throughout the country. One of the latest was a church bombing in Makassar in late March that injured dozens and killed the two suicide bombers.

Ahmad said during the briefing that the police had searched Munarman’s residence and the FPI secretariat’s office in Petamburan, Central Jakarta, and had found bottles of “powder containing high concentrations of nitrate in the form of acetone, as well as bottles of triacetone triperoxide (TATP) liquid”. The potentially explosive substances bore similarities, Ahmad said, to ones discovered during the arrest of four alleged terrorists in Condet, East Jakarta, and Bekasi, West Java, in late March.

He said the police would continue investigating the chemicals and documents discovered during the search.

Munarman became a lawyer for the group’s firebrand leader, Rizieq Shihab, after building his career at the Indonesian Legal Aid Institute Foundation (YLBHI) and the Commission for Missing Persons and Victims of Violence (KontraS). He was also closely linked to Hizbut Tahrir Indonesia (HTI), a group that was also disbanded by the current administration.

His arrest came four months into the FPI ban, which was enacted through a joint ministerial decree (SKB) signed by various ministers and heads of institutions, including the National Counterterrorism Agency (BNPT).

The government claimed the FPI had no legal grounds to operate as a civil organization because it had failed to extend its registration permit and that its activities were in violation of prevailing laws. It said these violations included the use of violence, illegal raids and public provocation. During a press briefing on the ban, the government presented a number of videos purportedly showing Rizieq’s support for IS, as well as footage of FPI members in Makassar allegedly pledging allegiance to IS.

While the group openly seeks the implementation of strict sharia law in the country, most FPI members share the more mainstream religious understanding of at least 60 percent of Muslim Indonesians, including with regard to rituals and base ideology, said Greg Fealy, associate professor of Indonesian politics at the Australian National University.

Greg said he feared that the ban on the group’s activities, the ongoing trial of Rizieq and the recent police shooting of six FPI supporters could create a greater risk of radicalization.

“We see this already. Within the FPI community, there is a conviction that the state is deeply hostile to Islam,” he said during a livestreamed discussion on Wednesday.

The ban was announced shortly after Rizieq’s return from self-imposed exile in Saudi Arabia in November 2020. He left the country in 2017, after he was named a suspect in both pornography and treason cases. The charges were later dropped.

Rizieq is now suspected of being responsible for planning and hosting crowded events upon his return in violation COVID-19 restrictions. If found guilty, he may face up to six years in prison.

One of the first figures he met after returning to the country was Jakarta Governor Anies Baswedan, a potential contender in the 2024 presidential election. Anies has been linked with the FPI, which is known for its opposition to the Joko “Jokowi” Widodo administration.

A few days before Rizieq was named a suspect in the COVID-19 restriction violation case, six FPI supporters were shot to death by the police in an alleged clash on the Jakarta-Cikampek toll road in the early hours of Dec. 7, 2020. Investigations are still underway, the police have said.

Fealy said that after these events, especially the killing of the FPI supporters, there had been an almost immediate shift in tone from the FPI community and social media sites, even among groups that had no previous run-ins with the police. He said the tone was more extreme and vengeful and that the shift was also apparent among former members of the FPI who had left the organization because of divergent beliefs, who planned bombings and other acts of retaliation.

The price of the state repression, Fealy said, was deepening animosity between law enforcement and militant Islamists, among other issues.

Aziz Yanuar, an FPI-affiliated lawyer who is representing Munarman, said that in 2015, his client went to Makassar only to attend an event on global politics as a guest speaker and that he had nothing to do with a baiat.

“Since 2014, the FPI has clearly opposed IS […] There were groups that still followed the ideology, but they eventually became inactive, and some were even kicked out,” he told The Jakarta Post on Wednesday.

He said the legal team had not yet gained access to Munarman and claimed the arrest had violated his client’s rights, as he was coerced and dragged out of his house.