Only hit men could have carried out the killing of Japanese national Hoshi Kunio, 66, claimed Rangpur's Additional Superintendent of Police Shah Mamtazul Islam.

Mamtazul, who is leading a CID probe team, outright denied the involvement of any militants in the murder of Kunio.

“Still, we are investigating the murder with an open mind … whether he had personal enmity or financial dispute or the murder was part of a militant operation … ,” said Mamtazul. 

Mamtazul was hopeful of discovering the motive of the murder in two days but refused to elaborate anything citing the pending probe.

Kunio was shot near his farm at Kaunia's Alutari village in Rangpur around 10:30am Saturday, five days after unidentified criminals shot an Italian aid worker dead almost the same way in Dhaka's Gulshan.

Police filed a murder case against three unknown attackers early yesterday.

The killers of Kunio used a rifled weapon to shoot him four times at close range.

“Rifled weapons are more effective in ensuring deaths than smooth-bore weapons,” said Rafiqul Islam, associate professor at the forensic department of Rangpur Medical College.

According to Rafiq, who led a four-member team that conducted an autopsy on Kunio's body at the RMC yesterday afternoon, a bullet fired from a rifled weapon spins on an axis giving it more range and a more stable trajectory.

Two Japanese nationals -- Dr Kursia Martiya and Japanese High Commission's chief security officer Kin Jur -- were present during the autopsy. The duo and Kin's personal secretary Abdur Rahman went to Rangpur Saturday night.

Two of the bullets had burst his liver into pieces and filled the abdomen to the brim with blood, Rafiq told The Daily Star.

The two bullets had pierced into the body through the right shoulder and the chest and exited through the back, revealed the autopsy.

“He was shot from a distance between five and seven feet,” said Rafiq. “Even his stomach was perforated and the death was due to haemorrhage and shock,” Rafiq added.

Two other bullets had hit Kunio's right wrist and ring finger.

The CID team, led by ASP Mamtazul, had collected evidence from the scene from around 7:00pm Saturday until 1:30am Sunday.

According to Mamtazul, a Rab team also worked at the crime scene at the same time and collected evidence for its own investigation.

Rab team leader Col Abul Kalam Azad, chief of the force's intelligence wing, could not be reached for comments.