One of the unwritten rules of the Mafia was Omer Ta, the code of silence.

It was forbidden to talk about the existence of the Mafia, to reveal how it worked, or name the main players.

The Mafia demanded loyalty from its members to the very end.

But when law enforcement started using modern surveillance techniques to incriminate mobsters,

the list of those willing to cooperate with authorities began to grow longer and longer.

It turns out mobsters do talk about the Mafia, even bosses, if it means saving their own skins.

In this bonus episode of Mafia, we'll look at how the police and FBI were able to crack the code of Omer Ta.

We'll look at some of the most high-profile rats in mob history,

and how the Mafia often ensured silence before these wise guys were even able to contemplate cutting a deal.

Finally, we'll look at what makes mobsters flip, despite knowing it could mean a contract on their head.

This is Mafia.

For a long time, the American public, even people within law enforcement, weren't aware that the Mafia really existed.

Remember that the mob, Kozenoster, was a secret society.

The law of Omer Ta, which everybody had to adhere to,

said essentially, you can't mention the existence of the mob or testify about anybody else.

Ron Goldstock is a former Mafia investigator.

And so there were inklings about it.

The E.A. more than any other federal agency at that time, the Bureau of Narcotics, knew somewhat about it

because they saw the traffic going back and forth between American organized crime and Italian organized crime groups.

Until the early 1960s, the real inner workings of the Mafia were largely unknown.

But by and large, no one knew really the names of it.

They saw the Union's Asyliana to be part of what they considered the underworld.

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