"We've identified the killer of BDR DG Maj Gen Shakil Ahmed and at least two others who gunned down other senior officers," the Daily Star newspaper quoted an unnamed investigating officer as saying.

He, however, declined to name the three but said they are already in custody. The officer said the three were involved in the killing at the onset of the mutiny, while they claimed a group of six to seven who first opened fire at the Darbar Hall were BDR soldiers and not outsiders.

Investigators earlier said they found clues that outsiders in uniform intruded the BDR headquarters ahead of the rebellion while a senior government minister overseeing the investigation process said Islamist militants might have a hand in the carnage.

Officials earlier said a BDR soldier who was believed to have killed Shakil's wife was arrested as so far 650 rebels were detected through video footage, interrogation of arrested soldiers and on the basis of the statements of survived officers and family members.

"Of the 650 BDR men, over 150 were directly involved in killings, looting of arms and explosives from armouries," an officer earlier said.