Jihadist spiritual leader Abu Bakar Bashir's influence over Southeast Asia's militants could be on the wane, after his sons denounced his allegiance to Islamic State, a group so brutal even al-Qaeda severed ties with them.
"On this matter of Islamic State, I have parted ways with my father," Abdul Rohim, Bashir's youngest son, told the South China Morning Post in a phone interview from Indonesia.
"I don't support him on Islamic State. Maybe on some other matters too. But as my father, of course I support him," Rohim added.
Bashir, 76, is the spiritual leader of the al-Qaeda-linked Jemaah Islamiah group blamed for the 2002 Bali bombings. In 2008, he founded the splinter group Jemaah Ansharut Tauhid (JAT). He is currently serving a 15-year jail sentence for terrorism offences.
Malaysian police say the teachings of Bashir and another convicted Indonesian militant, Aman Abdurrahman, inspired Malaysians to travel to Syria to join Islamic State.
"Many were influenced by the teachings of Abu Bakar Bashir to go to Syria. He is very extreme and influential," a senior Malaysian police source said.
One Malaysian going by the nom de guerre Abu Turab, 52, was killed in Hama, Syria on Tuesday. Malaysian police said his real name was Zainan Harith and he was a former member of the Malaysian Militant Group involved in a 2001 bank robbery.
Bashir's two sons quit their father's group last week and set up a new jihadist organisation named Jemaah Ansharusy Syariah because of their refusal to support Islamic State. The group will fight for the implementation of sharia law in Indonesia.
Indonesian director of operation for the National Counter-terrorism Agency, Police Brigadier General Petrus Golose said Bashir threw out members of his group if they refused to join the Islamic State. These fighters joined Bashir's sons, Rohim and Rosyid Ridho - the elder son, in their newly created group.
Tall, intelligent and articulate, Rohim is known to be skilled in IT, which he uses to expand his reach. He spent his formative years in Malaysia, where his father lived in exile from 1985 to 1998 as a fugitive from Indonesian authorities for opposing the government of late president Suharto. Rohim has spent time in Pakistan and Afghanistan, where he is believed to have received paramilitary training, according to former Jemaah Islamiah members and the United Nations Security Council.
"He is a future leader of jihadist organisations. Maybe not now but five to 10 years from now," said Ali Fauzi, a former Jemaah Islamiah member.
"He is smart and has the capability to manage and run an organisation. Add to that, he is the son of Abu Bakar Bashir, who is an icon," Fauzi added.
Fauzi's two older brothers, Mukhlas and Amrozi, were executed for their role in the 2002 Bali bombings that killed 202 people, including 11 Hong Kong residents. After his brothers' execution, Fauzi laid down arms.
"Rohim has lived and studied in Malaysia, Pakistan and Afghanistan. The understanding is that he received paramilitary training there (Afghanistan)," Fauzi added. "I have heard he has links with [militant group] Jabhat-al Nusra," Fauzi said.
Jabhat al-Nusra is linked to al-Qaeda and has fallen out with the Islamic State. Islamic State is reported to have executed and beheaded al-Nusra fighters in Syria.
One of Bashir's close associates, Mochammad Achwan, left him to co-found Jemaah Ansharusy Syariah with Bashir's sons.
"There are some 3,000 JAT members who have joined us. The number of members left in JAT must be around 5 per cent," Achwan said in a phone interview.
"We disagree with [Islamic State] as they do not represent a true Islamic state. Even Muslim clerics from the Middle East, including Yemen, Syria, do not recognise them," said Achwan.
While it appears large numbers of JAT members have abandoned Bashir and are refusing to support Islamic State, many remain drawn to its ideology, seeing the militant group as the fulfilment of a prophecy that a new Islamic order will emerge every 100 years.
They see the Ottoman Empire, which ended in 1922, as the last such Islamic order.
"I estimate there must be around 5,000 Islamic State members in Indonesia right now," said Fauzi.
However, some believe support for Islamic State will begin to wane.
"Any organisation that is too brutal will not be sustained. It will alienate the public," said Noor Huda Ismail, a counterterrorism expert who runs the only private deradicalisation programme in Indonesia.