I'm not a Fibbie, but I have photos of J. Edgar in a dress
Hey I'm just kidding. I think JEH was a heck of a guy. No need to investigate me for "subversiveness." Really
Why would FBI guys need a special knife? This is the "how long is a piece of string?" question
The process for getting in is (also check out their web page for detail):
Send in initial application - gives them basis background info on you (get this form by mail)
Take initial test. Pass it.
Receive LENGTHY background application. Do about a million hours of research on yourself, fill it in and send it in.
Assuming you are OK'd, go to next testing phase, including polygraph exam and physical fitness test.
(The PT test is different than the Marine's/Army's/Navy's - you'll need to practice)
Pass and go to Quantico for 16 weeks resident training course. Probably one of the best LE courses in the world (LAPD, is another)
Better like Marines, because the FBI Academy is on the Marine base and there's tons of former Marines in the FBI
Some requirements:
No or EXTREMELY limited "record" - and they check
No or extremely limited drug use - and they polygraph - better be NO "hard" drugs
You don't have to be a lawyer or an accountant, but they always need a bunch of both
If you are a lawyer, you're in a different pool than the other guys, who need a Bachelor's and experience.
Accountants (actual CPAs) are in a different pool, too (I think!)
The regular pool is the toughest - most competition.
Military helps, but is not a requirement, and doesn't get you into a different pool.
They are a strong affirmative action employer, so if you're in a special group, you're better off.