Indonesian militant Muhammad Bahrun Naim, whose name came up after yesterday's arrests in Batam, has been in the news since 2010, when he was arrested for illegal possession of ammunition.
He is now said to be fighting alongside the Islamic State in Iraq and Syria (ISIS) in the Syrian city of Raqqa, the de facto capital of the terrorist organisation.
The 32-year-old is believed to be a leader among militants in the Katibah Nusantara, a South-east Asian military unit under ISIS that recruits militants from Indonesia, Malaysia and other parts of the region.
Yesterday, the Indonesian authorities said that Bahrun and Gigih Rahmat Dewa, the leader of a Batam cell who was arrested, had plans to attack Marina Bay in Singapore.
In March, Singapore's Home Affairs Minister K. Shanmugam said in a speech that Bahrun was well-known to security agencies in the region, and was actively encouraging militants to launch attacks in Malaysia, Indonesia and Singapore.
In November 2010, Indonesian police's elite counter-terrorism unit, Densus 88, arrested Bahrun and seized hundreds of bullets from his home.
He was jailed for 21/2 years. The court, however, found insufficient evidence to pursue terror charges.
He disappeared after he served his time, and police believed he went to Syria. But he remains in close contact with domestic terror cells and militants in Indonesia.
Bahrun is from Pekalongan in Central Java, and worked as a computer technician and ran an Internet cafe in the city of Solo. Gigih is from Solo, also in Central Java.
Police believe Bahrun masterminded the brazen attack in Jakarta in January which killed eight people. A police spokesman said at the time that Bahrun had sent money back to Indonesia to finance the attack.
Bahrun was believed to have also taught Nur Rohman, the suicide bomber who blew himself up near a police station in Solo on July 5, to build bombs. A police officer was injured in the attack.
Indonesian police spokesman Agus Rianto yesterday said Bahrun had sent money to Gigih to finance radical activities. "Gigih was to carry out attacks on several places on Bahrun's order," he added. These include suicide attacks targeting public places and police offices.
In a Telegram exchange with Reuters news agency on Nov 24 last year, Bahrun said there were more than enough ISIS supporters to "carry out an action" in Indonesia. "Just waiting for the right trigger," he reportedly said.
Not long after that Telegram exchange, intelligence officials began to pick up talk in social messaging chatrooms that an attack on Indonesia was imminent.
In the same exchange, Bahrun said he enjoyed life in Syria.
"I move around, depending on where our emir orders us to go. It's good here in Syria.
"There's electricity, accommodation, water, and it's free. The services provided by them are good, cheaper than in Indonesia."