Retired Major Sinha Md Rashed Khan was shot at least four times and there was a brief pause between each gunshot, said investigators, attributing that Sinha was murdered intentionally, not accidentally.
Referring to the autopsy report, they said the then in-charge of Baharchara Police Investigation Centre Inspector Liakat Ali shot the former major dead "intentionally and ferociously".
"Liakat did not fire the shots at the same time. Rather, multiple shots were fired with pauses," an investigator told The Business Standard Sunday night on condition of anonymity.
"If you have to fire in self-defence, you will continue shooting until the threat is neutralised. But if the shooting is premeditated and you are furious, only then you will fire with gaps between each shot," he explained.
RAB-15 official Md Khairul Islam, investigation officer of Sinha murder case, said there were six wound marks on the body, which means the slain ex-army official might have been shot at least four times.
While talking to The Business Standard, both a forensic expert and the forensic department head of a medical college hospital said the shooting pattern hints that the shooter was so ferocious at that moment.
A retired forensic expert of a law enforcing agency said, "There is a difference between gunshots fired in self-defence and shots fired in cold blood to kill someone. Sinha's bullet wounds and the postmortem report indicate that something went wrong. The shooter might have fired intentionally."
A law enforcing agency source said Inspector Liakat shot Sinha with his Taurus 9mm pistol made in Brazil.
He said that Liakat and Nandadulal Rakhsit – both accused in the murder case – returned their arms and ammos to Teknaf police armory as usual after the shooting incident on Cox's Bazar Marine Drive on July 31 night.
"Liakat mentioned he used four rounds of bullet among the issued 30 rounds while Nandadulal submitted all the 30 bullets issued with his gun," added the source.
Previously, Additional Director General (Operations) of the Rapid Action Battalion (RAB) Colonel Tofail Mostafa Sarwar said Sinha was gunned down in just one and a half minutes.
"The killing of Major Sinha is being analysed deeply. Every second of this one-and-a-half-minute incident is very important," he added.
Liakat, Pradeep blaming each other
Another source close to the investigation told The Business Standard that the two prime accused, suspended Teknaf Police Officer-in-Charge Pradeep Kumar Das and Inspector Liakat Ali, were blaming each other for Sinha killing.
"Pradeep told investigators he informed Liakat that robbers came down to locality from the hill and asked him to check out. But Liakat claimed that he was instructed by the OC to shoot," said the source.
"This could be their trick to survive the interrogation. We are analysing and cross-checking every piece of information gleaned from them," he added.
Interrogation of APBn men to cross-check info
Lt Col Ashique Billah, director of RAB Legal and Media Wing, told The Business Standard Sunday that they were interrogating the three Armed Police Battalion (APBn) members who were arrested on August 17.
"For scrutinising the information gleaned from seven accused, we will thoroughly interrogate the APBn members. Investigators will also cross-match and verify the information to reach a conclusion," he added.
RAB took the three members of Cox's Bazar Armed Police Battalion (APBn) into custody on Saturday for questioning. They are Assistant Sub-Inspector Shahjahan and two constables – Rajib and Abdullah.
The trio were on duty at the APBn checkpoint on Marine Drive when Sinha was killed.
Major (Retd) Sinha and his three-member team had been in Cox's Bazar to make a documentary film. On July 31 night, Sinha was killed in police firing.