MELBOURNE, Fla. -

Inventory of surplus military rifles came up short for the Melbourne Police Department.

Florida Today reports the police department was supposed to have 65 M16 assault rifles.  Only 64 of the rifles were accounted for. 

The error was discovered during the required annual audit that started in December. 

According to authorities, searches for the rifle turned up with nothing along with a search for the gun's serial number into a federal database. 

The Melbourne City Manager says the police department has launched an investigation and he's working to help figure out what happened to the rifle.