Jakarta. State prosecutors have detained businessman Samin Tan as a suspect in an alleged corruption case tied to the management of coal mining operations at Asmin Koalindo Tuhup, authorities said early Saturday.

Investigators from the Attorney General’s Office’s special crimes unit took Tan into custody after finding sufficient preliminary evidence of alleged irregularities in coal mining activities in Murung Raya, Central Kalimantan, between 2016 and 2025.

“We have officially named ST as a suspect,” said Anang Supriatna, head of the Attorney General’s Office Legal Information Center, during a press briefing in Jakarta.

The case was upgraded to a formal investigation on March 25, according to Syarief Sulaeman Nahdi, director of investigations at Jampidsus. Authorities have since questioned multiple witnesses and carried out searches across several regions, including West Java, Jakarta, South Kalimantan, and Central Kalimantan.

Search operations are ongoing, particularly in Kalimantan, Syarief said.

Prosecutors suspect the case involves collusion with public officials tasked with overseeing mining activities. “The alleged violations were not carried out alone. We have indications of involvement by state officials responsible for supervision,” Syarief said, adding that such collaboration underpins the classification of the case as corruption due to potential losses to state finances and the broader economy.

Authorities have not disclosed the identities of the officials allegedly involved, and no additional suspects have been named.

Tan is described as the beneficial owner of Asmin Koalindo Tuhup, a coal mining company that previously operated under a Coal Contract of Work (PKP2B). The firm’s permit was revoked in 2017, but prosecutors allege that it continued mining and selling coal illegally through 2025 using invalid licensing documents and with the involvement of certain officials.

“The actions were unlawful and potentially caused losses to state finances and/or the national economy,” Syarief said.

The total state losses remain under calculation by Indonesia’s Financial and Development Supervisory Agency (BPKP).

Tan has been charged under Articles 603 and 604 of the Criminal Code and will be held for 20 days at a detention facility operated by the Attorney General’s Office in Jakarta pending further investigation.

Once ranked among Indonesia’s wealthiest individuals, Tan built his fortune through coal ventures, including ownership of Borneo Lumbung Energi. He also served as chairman of Bumi Plc, a London-listed mining firm, during the peak of his career.

According to Forbes, Tan was listed as Indonesia’s 28th richest person in 2011, with an estimated net worth of $940 million.