The man, from the Javanese city of Solo, also known as Surakarta, is looking to assert himself as a major regional player in ISIS' planned "distant caliphate
The former blogger has spent time in prison, and has a history with radical groups, they say, adding that they believe he plotted Thursday's attack to assert himself among various figures competing to lead ISIS in Southeast Asia.
Others include Bahrum Syah, believed to be commander of Katibah Nusantara, a joint Indonesian-Malaysian fighting unit formed in late 2014. Another is Abu Jandal, a preacher from Malang to whom Naim had links, before his ambition outgrew the influence of the iman.
Jakarta police chief Tito Karnavian told CNN that Naim went to Syria after he got out of prison.
He was apprehended by Indonesian authorities in 2010 for illegal possession of ammunition and was brought to justice, the police chief said. Naim was sentenced to at least 2½ years behind bars.
Extremist positions gathering pace
The police chief did not provide additional details on Naim's life, but Sidney Jones, director of the Institute for Policy Analysis of Conflict, filled on some of the blanks in an email to CNN.
Based on her account, Naim was born September 6, 1983 in Pekalongan, Indonesia. He grew up in Solo and studied computer technology in college.
Naim was reportedly close to the son of Abu Bakar Bashir, the radical Indonesian cleric who founded Jemaah Islamiyah, the group that orchestrated the 2002 and 2005 Bali bombings.
Maim is said to have joined Hizbut Tahrir, a conservative Islamic group, but then left the group.
The ammunition that Naim was arrested for in 2010 was used by men involved in an attack on police in Central Java, according to Jones. Two years after his release he, and his secret wife, pharmacy student Siti Lestari, fled to Syria. He left behind an existing wife, and two children.
From Syria, Naim financed an ultimately unsuccessful, inept attempt at a series of bomb attacks in Solo. He later sent money to would-be jihadists looking to travel to Syria.
Police arrested several men, included a Uighur whom the Indonesians had persuaded to be a suicide bomber, but several remained at large.
Jones says that, while living in Solo, he developed a reputation as a radical teacher and maintained an active blog.
Following Thursday's attack, an Indonesian anti-terror source told CNN it was "highly possible" a particular blog is run by Naim himself or by people posting on his behalf.
The blog, written entirely in Bahasa Indonesia, contains ISIS teachings, posts on how to conduct terror attacks, lessons learned from the Paris attacks, how to avoid intelligence surveillance, how to make homemade pistols and how to conduct guerrilla warfare in cities.
Authorities in Indonesia have been monitoring the blog for two years, the anti-terror source said.