JAKARTA - Two bombmakers who made the device used in the suicide bombing of police headquarters in Medan, North Sumatra, last week have been killed in a police raid, laying to rest initial suspicions that the attacker acted as a "lone wolf."
Investigations uncovered that the suicide bomber was linked to the Islamic State in Iraq and Syria (ISIS)-affiliated local network called Jemaah Ansharut Daulah (JAD), which was founded by terrorist ideologue Aman Abdurrahman who is now on death row.
Identified by the police only by their initials KA and P, the bombmakers had hand-made firearms and resisted arrest during the raid on Saturday (Nov 16) which left one policeman injured. Three accomplices of the bombmaker who were with them during the raid in Deli Serdang regency, about an hour from Medan, were arrested and are being interrogated.
Between last Wednesday's attack and Saturday, police have rounded up 43 militants. Twenty were nabbed in North Sumatra and neighbouring Aceh province while another 22 were arrested in Java. One militant was detained in East Kalimantan, said police.
The attack last Wednesday occurred at around 8.40am local time, 20 minutes after the bomber was seen on closed-circuit television walking into the police compound.
The young man, clad in a ride-hailing service jacket and carrying a big backpack, blew himself up in a carpark near a building where certificates of clearance, known as SKCK, were being processed. Police later identified the perpetrator as RMN.
Six people - four police officers, one police employee and one civilian - were hurt in the blast, which also damaged several vehicles. Eyewitnesses told local media they heard a loud explosion and saw white smoke as they rushed out of the building.
Among the 20 arrested was a senior militant that police identified as Yanto, alias Yasir, who is the leader of JAD for North Sumatra and Aceh.
"Yanto is a leader. He led others to pledge allegiance to the ISIS leader. He also led a paramilitary training on Mount Sibayak (North Sumatra)," national police spokesman, Inspector General Dedi Prasetyo, told a media briefing on Monday (Nov 18).
North Sumatra police chief, Inspector General Agus Andrianto, was quoted as telling reporters separately that the militants practised shooting arrows and horse riding at the paramilitary training camp.
But kompas.com said the general was baffled by the training on horse-riding and how that was connected to a terror attack plan.
Police investigations also found that Yanto communicated with a terrorist inmate in Medan prison, bought equipment needed for the Sibayak paramilitary training camp and purchased materials needed to make bombs.
The other militants rounded up by police were those who either knew about the planned suicide bombing on Wednesday, or took part in the paramilitary training on Mount Sibayak.
"North Sumatra has various terrorist factions. The pro-ISIS ones are quite a few," anti-terror analyst Adhe Bhakti told The Straits Times.
Earlier this year, in March, police found 300kg of explosives and more than 15 bombs in two houses belonging to a detained terrorist and an accomplice in northern Sumatra.
The materials - which included a land mine, pipe bomb and vest bomb - were mostly found in the Sibolga home of local militant cell ringleader Husain alias Abu Hamzah, 30, whose wife later blew herself up with her two-year-old child, as the house was besieged by police.
