Imam Samudra - sentenced to death for organising the Bali bombings and executed on 8 November 2008 - is remembered in his home village as a studious child, but prone to occasional emotional outbursts.
Imam Samudra was the only suspect with a university degree
Born Abdul Aziz, he grew up in Serang, west Java, raised by a single mother as one of 12 children.
Though he has barely been in contact for 12 years, his mother, Embay Badriah, said she could not believe her son, now 33, could have played a part in the deadly attack, in which more than 200 people died.
Imam Samudra graduated from his Islamic school with flying colours.
A former teacher, A Fathoni, told Metro TV: "He was always a star of his class, at the top rank, for the first, second and third year he was here.
"He came from a not so well-to-do family, but he was very active in his studies."
The suspect's older sister, Alyiah, said police must have fabricated evidence showing his involvement in the Bali plot.
"He studies a lot, is very calm, and prays every day," she said soon after his arrest.
"But when he was a child, he easily got upset and cried a lot."
Imam Samudra left home in 1990 and did not return for a decade - and then only for a few hours before disappearing again, according to his mother.
It is during that intervening 10 years that police said Imam Samudra - who uses at least six other names - became involved with alleged militant leaders.
He went to Malaysia and taught at a religious school in the south of the country in the early 1990s.
Indonesian authorities say the school was run by the suspected leaders of the militant Jemaah Islamiah group - Abu Bakar Ba'aysir, the group's spiritual leader, and Riduan Isamuddin, also known as Hambali.
It remains unclear what role, if any, Imam Samudra played in Jemaah Islamiah. The indictment against him makes no mention of the network
Mr Ba'aysir has denied having any ties to the organisation blamed for a series of church bombings as well as the Bali attack.
Foreign governments have linked Jemaah Islamiah to al-Qaeda. According to prosecutors, Imam Samudra travelled to Afghanistan to learn bomb-making and fight for the Taleban.
They said he used those skills in the bombings of Indonesian churches in 2000 - attacks which Mr Ba'aysir is accused of orchestrating.
Police alleged that the calmness remembered by his sister turned into a cold-blooded single-mindedness.
The only one of the suspected bombers to have a university degree, Mr Samudra was portrayed by authorities as the quiet intellectual of the group.
They said he even stayed in Bali for days after the bombing to survey the devastation he wrought and observe the reactions of people he affected.