Tonight on Best Kept Secrets, we go inside one of the world's most secretive crime-fighting organizations, the Federal Bureau of Investigation. How does the FBI solve cases like the Oklahoma City bombing?

Unfortunately in the United States, it's very easy to build a bomb, all the components are verily available whether it be from a hardware store or a hobby store.

He revealed the secrets of the FBI's Explosives Unit, plus how the FBI foiled this gang's murderous plan to destroy an oil refinery?

"My incentive of going to FBI was to save lives."

And can this criminal profiler help the FBI catch a cold-blooded murderer?

There was an indentation on one side of the face and not the other and there was a furrow in the brow.

Plus the high-tech spy gadget that the FBI use to track down a band of dangerous cyber crooks.

With the magic box, we're able to see all the things that they were sending back and forth each other, ah, all the computer systems that Calvin was hacking into.

And the FBI confronts the most heavily armed militia that US law enforcement has ever faced. As we reveal the secret strategies of an FBI crisis negotiator.

If we can negotiate a person now, it's much better than have to go in and drag him out, maybe shoot him.

These stories are straight ahead on Best Kept Secrets.

There's nothing mysterious about the manner in which the Federal Bureau of Investigation works. Its formula is a simple one: intensive training, carefully investigated and highly efficient personnel plus rigid requirement in regard to conduct, intelligence and integrity.

G-men, tommy guns, public enemy No.1. Since 1908, the FBI has enforced provision and waged bloody battles with the likes of "Baby Face" Nelson and John Dillinger. Under a legendary chief J. Edgar Hoover, the bureau created the nation's first crime-fighting laboratory and developed the field of forensic science. And today the FBI employs 23,000 agents, the largest crime-fighting force in the nation.

FBI, come out, put your hands up.

Its headquarters is located here, in the heart of Washington DC, in a building that occupies an entire city block. Behind these close doors, agents use the latest in science and technology to combat crimes ranging from domestic terrorism to cyber crime.

Put your hands behind your back.

Tonight, we examine the FBI, from the files of actual cases, we'll reveal the crime-fighting secrets that have made the FBI the most powerful law enforcement agency in the world.

hobby store: is a place dedicated to the selling of things that people usually employ for their personal satisfaction. Hobby stores are particularly popular with men and children, less so with women, although many hobby stores today cater to women's interests too.