The safe was left battered, possibly by a hammer, but remained secure during an April 2 break-in.
"It looked like they were just looking for money," says Cpl. Jim Forsey of the Hay River RCMP Detachment.
The break-in occurred between 4-9 a.m. A window near the front entrance to the building was smashed to gain access.
At about 8 a.m. on the same morning, there was also an attempted break-in at the reserve's Chief Lamalise Complex.
Police believe the two incidents are related.
No arrests had been made as of late last week, but the investigation is continuing.