Investigators have begun interviewing hundreds of other border guards who returned to their compound days after fleeing the scene of the attack, Brigadier-General Ziaul Hasan said.
The army is still searching for more than 1,000 border guards who are yet to return to their barracks.
Sheikh Hasina, the Bangladeshi prime minister, has said that the mutiny was part of a conspiracy against her two-month old government.
She has said that the border guards may have had outside help, but has not said who she suspects of being linked to the planning of the mutiny.
"We must remain alert, so no one can take away the rights of the people," Hasina told supporters on Tuesday.
The Bangladeshi government has called for help from the US and the Federal Bureau of Investigation (FBI) in probing leads into the attack.
The FBI is considering Dhaka's request, Richard Kolko, an FBI spokesman, said.
At least 55 army officers and wives were among those killed in the revolt by the border guards, which was apparently sparked over poor pay and conditions.
Army officers receive higher pay, longer holidays and more food subsidies than the border guards.
The delicate relationship between the army and the government could falter as the investigation continues, analysts have said.
The military which handed over power to an elected government two months ago, is thought to be unhappy at how Hasina handled the crisis.