Which organizations are close to X-COM in the early game?
Classic X-COM is quite clear to be Spec Ops, with a backing of more "investigative" types in the background - which is probably where all these UFO Report charts and the odd "Alien Base Found in X" at end of the month comes from.
Here's FBI ranks, for comparison:
Field Agents
Probationary Agent
Special Agent
Senior Special Agent
Supervisory Special Agent
Assistant Special Agent-in-Charge (ASAC)
Special Agent-in-Charge (SAC)
There's the problem that this is all Agent Agent Agent Agent. Repetitive.
Looked at russian ranks for FSB and such, but they're pretty military.
I'm not really the best person to talk about this, because in Brazil, we have a military and a civilian police branch. The military one are the guys that do ostensive policing, while the civilian branch handles investigations. There's also the Federal police but these guys are more after big crime - big drug traffic, white collar crime, etc. They also have a special anti-terrorism unit, the COT. They would be the Brazilian FBI, so to say.