He could hardly fail to notice the activities of the Camorra, who treat such estates as their own. They deal in drugs, extort protection money, and traffic in prostitutes and illegal immigrants.
By his own account, the teenage Saviano was galvanised by rage against the amorphous criminal entity also known as "the System" when it murdered the parish priest in his own church.
Operatic gangster movies about "the friends of friends" over the water in Sicily have schooled us in soupy notions of respect and honour. But it seems as though the Camorra doesn't work like that - with an extended family, and an implacable godfather ensuring order.
The massive profits to be made from drugs, and the unhinging effects of mobsters sampling their own wares, have instead turned the impoverished neighbourhoods of Naples into a battleground.
Visiting murder scenes
The city's mortuary truck, "the death-catcher van", as Saviano calls it, makes a fresh collection once every three days.
So there was no rite of initiation for the brave author to bluff his way through, no code of "Omerta" to violate. He knew everyone in the tenements; they recognised him as a guy from around the way.
He went out at night on his Vespa, first to the scene of each fresh homicide, and then he wrote it all up in what he calls his "non-fiction novel".
His mistake, if that's what it was, was to name names, and to be successful.
When Newsnight met him in secret for his first interview on British television, he looked back with mixed feelings on a slightly younger self who had wanted to feel "the hot breath of reality" on his neck.
Saviano reflects on writing his book and how it has changed his life
Saviano's armed escort, his constant companions, kept watch.
"What's the police cooking like?"
He cracked a smile.
"Oh, it's meat with pepperoni, pasta with pepperoni. Everything with pepperoni!"
In recent weeks, a concert has been staged in Naples in support of the writer, and Nobel laureates have spoken out in his defence.
He also received a word of advice from a British author who knows a thing or two about going into hiding over a book.
"I met Salman Rushdie in New York and he told me a wonderful thing I have never forgotten, a truly important thing, how to come through this situation. 'Freedom is in your mind, if you lose it once, you have lost it forever. Keep it and you will be free.'"