Besides Tumsanga, an IPS officer of West Bengal cadre, former Additional Superintendent of Police Tlangkunga was also arrested yesterday, they said.
The chief judicial magistrate here granted interim bail to the duo on the condition that their bail plea would be heard within 30 days.
Both the police officers are now retired.
The arrest culminated a Gauhati High Court order to set up an inquiry commission based on a PIL, ACB sources said.
The state home department submitted an FIR in the case on December 16 in accordance with the recommendations of the inquiry commission, they said