Cox’s Bazar Judicial Magistrate Court recorded his confessional statement under Section 164 of the Code of Criminal Procedure, said sources of Rab.
Later, the court sent him to jail.
Earlier, Inspector Liaqat Ali of Baharchhara police outpost on Sunday gave confessional statement in the case.
With this, five people including two top officials of Armed Police Battalion (APB) made their confessional statements before court.
Besides, the court also put suspended OC Pradeep Kumar on a one-day remand in the case after expiry of his 3-day remand.
On Friday, the court placed Pradeep Kumar Das, suspended Officer-in-Charge of Teknaf Police Station, Inspector Liaqat Ali of Baharchhara police outpost and Sub-inspector Nandadulal on a three- day fresh remand over the killing.
The trio was earlier put on remand on August 24.
The authorities on August 2, suspended 21 police officials, including the in-charge of Baharchhara police outpost, in connection with the killing.
Major (retd) Sinha was killed in police firing at Baharchhara police check-post on July 31.
Sharmin Shahriar Ferdous, elder sister of Sinha, filed the case at Teknaf Senior Judicial Magistrate Court on August 5.
Also read: Major (retd) Sinha killing: Liaqat gives confessional statement