What could be Indonesia's largest graft probe revolves around the embezzlement of more than 2 trillion rupiah (S$205.5 million), or nearly half of the 5.9 trillion rupiah Parliament approved to pay for the national e-KTP project.
KTP stands for kartu tanda penduduk, or identity card in Bahasa Indonesia.
The biometric cards were supposed to be issued to Indonesians aged 17 and above, as part of a smart nation initiative mooted in 2009, during Dr Susilo Bambang Yudhoyono's presidency.
Many complained that they had to wait a long time to receive their cards, and when they did, they found the quality wanting, with most cards fading or peeling easily.
The Corruption Eradication Commission (KPK), which started investigating the project in 2014, said the case could be the largest graft scandal in Indonesia's history.
At least 37 high-profile Members of Parliament are said to have received millions of dollars in kickbacks from deals linked to the supply of the e-KTP.
House Speaker and Golkar party chairman Setya Novanto is among six individuals and the third lawmaker identified as suspects.
The others are Home Affairs Ministry officials Irman and Sugiharto, businessman Andi Agustinus, and lawmakers Markus Nari and Miryam S. Haryani.
On Thursday (July 20), Irman and Sugiharto were sentenced to seven and five years in jail respectively after they were found guilty of graft. Irman was also fined 500 million rupiah, while Sugiharto was fined 400 million rupiah. Both men said they will appeal the verdict.
Mr Setya, who was declared a suspect on Monday night, has denied any wrongdoing.
When KPK chief Agus Rahardjo was asked yesterday if more suspects would be rounded up, he said: "It is not unlikely... we are just waiting, waiting for the result of investigations (which) could provide grounds for further action."