My PD had 59s and when the Gen 2 came out they bought 659s. Some old timers wanted blue but they had to buy the 459 on their own dime. 469 and 669 were approved for off duty carry.
A lot of Agencies issued the 459 and 659. So I don't think it's a FBI pistol but from another Agency. Also most Agencies allowed officers to buy their own duty pistols in the 1980s.