Jakarta. One of the two men allegedly involved in the fatal stabbing of a police officer in Medan, North Sumatra, on Sunday (25/06) reportedly spent six months in war-torn Syria.

"He was in Syria for six months. This information has been confirmed by [the suspect] Syawaluddin Pakpahan and his wife," North Sumatra Police spokeswoman Sr. Comr. Rina Sari Ginting said in Medan on Monday.

This may be first time known case of an Indonesian returning from Syria carrying out an attack in the archipelago. Hundreds of Indonesian citizens are believed to have traveled to areas of Syria controlled by the radical Islamic State group.

National Police chief Gen. Tito Karnavian previously said the two suspects, Syawaluddin and Ardial Ramadan, are part of the Jamaah Ansharut Daulah (JAD) terror network, believed to be run by militant Bahrun Naim, who is currently in Syria.

The North Sumatra Police spokeswoman said Syawaluddin, who is still undergoing medical treatment for a wound he sustained after being shot by police during the attack, went to Syria in 2013, a year before IS announced the establishment of a caliphate straddling Iraq and Syria.

He has been in communication with his colleagues in Syria since returning to Indonesia.

"They communicate through the internet. Their targets include the police and the Indonesian Military [TNI]. If they were able to seize firearms from these institutions, they could kill personnel," Rina said.

The two suspects allegedly attacked police officers at a security checkpoint in front of the North Sumatra Police headquarters early on Sunday morning, hours before the prayer marking the start of Idul Fitri. The officer who died in the attack has been identified as Martua Sigalingging.