Indonesia's police have said the attacks were masterminded by Bahrun Naim, described as an "intellectual jihadi." A broader support apparatus in the world's most populous Muslim country is said to have played a role.
National police chief General Badrodin Haiti said on Friday that an attack carried out by militants in Jakarta was funded by the "Islamic State" militant group.
The funds were driven through Bahrun Naim, an Indonesian militant arrested in 2011 for illegal arms possession, the police chief told reporters. He served three years in prison for the charges.
After his release, he became increasingly involved in Islamist groups across the world's most populous country, emerging as a key player in militant networks. Naim left for Syria last year to join the fight alongside the "Islamic State" after being released.
Haiti added that while Naim is believed to be the mastermind of the attacks, police suspect a broader support apparatus in the country.
"The planners, financiers and supporters that provide [explosive] materials, assemble the bombs, facilitate accommodations and vehicles, etc … of course this is the work of a team that could be big or small," Haiti said.
"This obviously was not conducted by five men, this takes teamwork," Haiti added.
Fugitive terrorism suspects
The findings come as police arrested three men suspected of links to Thursday's attacks following raids across the country.
Two of the five men involved in the attack were fugitive terrorism suspects, police added.
On Thursday, five men launched a series of attacks in Jakarta's business district that left, at least one Indonesian and one Canadian dead and some 20 people injured.
The attack was immediately claimed by the "Islamic State" militant group, which has occupied large swathes of land in Iraq and Syria in its quest to carve out a "caliphate."
The 'intellectual jihadi'
In November, Sidney Jones, director of the Jakarta-based Institute for Policy Analysis, noted that there were signs of growing interest in the "Islamic State's" overall aims in Indonesia by local militants.
Jones, who described Naim as an "intellectual jihadi," wrote in a blog post for Australian think tank the Lowy Institute that he "urged his Indonesian audience to study the planning, targeting, timing, coordination, security and courage of the Paris teams."
Indonesian authorities have described the Jakarta attacks as an attempt by local militants to emulate November's "Islamic State"-claimed assault in Paris that left 130 people dead.
However, authorities added that due to the death toll, it showed that the local militants had negligible training in conducting similar attacks.
ls/jil (AP, AFP, Reuters)