Three men whose families carried out terror attacks, or were planning to, in East Java on Sunday and Monday previously visited the country's two most dangerous radical clerics, Aman Abdurrahman and Abu Bakar Bashir.
A source told The Straits Times that the three - Dita Oepriarto, Tri Murtiono and Anton Ferdiantono - travelled together on Jan 18, 2016, with others to the Nusakambangan island prison to meet Bashir. They met Aman the following day.
"The group requested to visit Rois, alias Iwan Darmawan, but cellmate Aman Abdurrahman joined in the discussion," the source said, referring to the convicted terrorist who is on death row for his role in the 2004 Australian embassy suicide bombing that killed nine.
Two of the three families carried out plans to sow terror in Surabaya, Indonesia's second-largest city.
On Monday, Tri and his wife and children, including an eight-year-old identified as Aisha, mounted a suicide bombing at the Surabaya police headquarters, injuring five innocent people at the scene and killing four of the suicide bombers. Aisha survived after being flung vertically by the blast.
The attack came while Indonesia was still reeling from the shock of suicide bombings carried out at three churches on Mother's Day, as people were going to church, by Dita, his wife and their four children. Twelve victims died in those attacks.
Later on Sunday night, Anton mishandled a highly explosive device that exploded prematurely at his flat in Sidoarjo, a town neighbouring Surabaya, before he could carry out a planned attack. The blast killed his wife and his eldest son.
Police gunned down the injured Anton, who tried to detonate another bomb as they arrived. Anton's three younger children survived and are being treated in hospital.
Police launched a series of arrests and raids in East Java and South Sumatra after the attacks, nabbing 13 militants and killing two others, national police spokesman Setyo Wasisto said yesterday afternoon.
Bashir, aged 79 and sickly, is the founder of South-east Asian terror network Jemaah Islamiah. He was sentenced to 15 years' jail in 2011 for inciting others to commit terror acts and helping to fund a paramilitary training camp in Aceh that was raided by the police.
Aman, who is in his 40s, is the founder of the Islamic State of Iraq and Syria affiliate, Jemaah Ansharut Daulah. He is on trial for masterminding a 2016 terror attack in central Jakarta that killed four bystanders as well as other attacks in Indonesia. He is due to appear in court on Friday.
Under Indonesian laws, all inmates including convicted terrorists may have visitors, but in 2016, the government decided to restrict visitations to high-profile terrorist ideologues, including Bashir and Aman. They were moved to isolation cells and were allowed to receive only immediate family members.
The three men involved in the latest blasts were in a group of nine who met Bashir weeks before he was transferred to an isolation cell. Another of the nine, Budi Satriyo, was killed in Sidoarjo when he resisted arrest in a raid on Monday. Police later found six ready-to-use pipe bombs at his home.
At the second meeting, the trio were with two other people.
Correction note: An earlier version of this story said a source told The Straits Times that the trio - Dita Oepriarto, Tri Murtiono and Anton Ferdiantono - travelled together on Jan 8, 2016, with others to the Nusakambangan island prison to meet Bashir. It should be Jan 18, 2016. We are sorry for the error.