Investigators have seized two projectiles from the Boeing 737-800 Biman aircraft, which Polash Ahmed reportedly tried to hijack on February 24 at Chattogram Shah Amanat International Airport.

The investigators have also collected the conversation between the pilot and the control tower of the airport in written form, said police and airport sources.

Earlier, Civil Aviation Secretary Md Mohibul Haque said the aircraft was hit by two bullets and a switchboard was damaged during the shooting.

Confirming the incident, Inspector Rajesh Barua of Counter Terrorism unit of Chattogram Metropolitan Police (CMP), also the investigation officer of the case, told The Daily Star, “The aviation engineer of Biman Bangladesh handed over two projectiles to us and we seized the items for investigation.

“Procedure is underway to send the projectiles for forensic test. We are trying to collect experts' opinions to identify which type of firearms the bullets were fired from,” Inspector Rajesh said.

Asked about the audio conversation between the pilot and the control tower, he said, “We have collected the conversation to verify some information.”

The official refused to make further comment over the matter.

According to the airport and police sources, the pilot contacted the control tower regarding the hijack at 5:29pm. In the 11-minute-long conversation, the pilot briefed the control tower mentioning an inside situation and requested action. The conversation ended at 5:40pm, said the sources.

Polash apparently tried to hijack the flight on Sunday, forcing an emergency landing at Shah Amanat International Airport.

All 148 passengers were evacuated safely and the cabin crew were also safe.

Polash was killed afterwards in an eight-minute operation by the para-commando unit. However, the gun held by the hijack suspect was found to be a toy gun later.

Debabrata Sarker, technology assistant at Shah Amanat International Airport, filed a case on Monday night with Patenga police. The case says the suspect was seen carrying suspicious objects during the hijack bid 15 minutes after the plane took off from Dhaka.