Even way back when in the 14th Century, the Maremma marshes and woods were home to bandits preying on the pilgrims to and from Rome. In fact, Dante places a certain Rinieri da Corneto (modern-day Tarquinia) in the circle of violent criminals (bandits, thieves and predators) in his Divina Commedia (Hell XII, 136-8):

"...e per l'eternità spreme le lagrime, che fa sgorgare con il supplizio del sangue bollente, a Rinieri da Corneto, a Rinieri dei Pazzi, che resero così pericolose le strade. "

"...and for eternity (God) forces tears, by means of the river of boiling blood, from Rinier da Corneto and Rinier Pazzo, highwaymen who made the roads so dangerous."

Dante also used the area as his model for the forest of the suicides (Hell XIII, 1015 et seq.), thanks to its wild landscape, with thick woods and briars, the kingdom of the wild boar:

" Non fronda verde, ma di color fosco;non rami schietti, ma nodosi e 'nvolti;non pomi v'eran, ma stecchi con tòsco. Non han si aspri sterpi nè si folti quelle fiere selvagge che in odio hanno tra Cecina e Corneto i luoghi colti".

"Foliage that's not green, but murky; branches that aren't smooth, but gnarled and tangled; no apple trees, but poisonous thorns. Such snarled, impenetrable thickets are the lair of the savage wild beasts that scorn the open fields between Cecina and Corneto."

It was only towards the end of the 19th Century that the Maremma was finally freed of the Brigands. Today there's a series of nature trails celebrating these "infamous" individuals: the Sentiero dei Briganti.
One of the most famous was Domenico Tiburzi, born in Cellere on the 28th of May 1836 (the subject of a film by Paolo Benvenuti).
Called "the King of Lamone" (the wild woods, now the Lamone nature reserve between the towns of Ischia and Farnese near the Tuscan border), he plagued the pilgrims heading for Rome in the period before the Unification of Italy. A sort of Robin Hood (according to local legend), he started his criminal career when the regional states abolished the peasants' rights to hunt and cut wood in the forests, fish in the rivers and garner the crops left in the fields after the main harvest. Thousands of peasants suddenly found themselves "outlaws" and starving.

Tiburzi committed his first "crime" at the age of 15, when he stole a fistful of hay from the Marchese Guglielmi to feed his father's starving donkey! His first murder was in 1867 when he killed a bailiff who'd fined him twenty Lire (a lot of money in those days) because Tiburzi's herd of cattle crossed over onto the land of the Guglielmi family.
At that point he became a proper outlaw, often donating the spoils to the poor. He had a definite idea of justice: "I, Domenico Tiburzi, fight for justice, even when this means going against the law". In fact, Tiburzi wasn't particularly cruel or bloodthirsty. He was, however, an excellent organiser: his band was run like a business. He acted as President, the Managing Director was a certain Domenico Biagini and there was even a Board of Directors (three of which were assassinated after betraying the "company": Pastorini, Basili and Bettinelli).

In 1872 he escaped from the jail in Corneto (Saline di Tarquinia) together with his companions. In the end he was liquidated by some of the local nobles (for whom he had often acted as a "bravo" - hired thug). The night of the 23rd of October 1896, he was ambushed by the Carabinieri in a house near Capalbio. During the shoot-out, Tiburzi was shot in the leg. What happened next isn't clear: was he murdered or did he commit suicide?
A great mystery surrounds his body: more than a century later his tomb still hasn't been found. The most accredited version goes that the parish priest of Capalbio refused to bury him, but the local community demanded that their "hero" be buried. A compromise was reached: the body of Domenico Tiburzi should be buried under the cemetery gate, his legs inside, his head and chest (and thus his soul) outside, without a tombstone. In later years the cemetery was expanded and all traces of the original gate were lost to memory.

Here's Tiburzi's version of the 10 commandments
(according to Piero Bargellini, writer, major of Florence in 1966 and senator):

I am Tiburzi, the maremmano bandit.
The Maremma shalt not have no other bandits before me.
Thou shalt not take the name of Tiburzi in vain.
Honour the lords of this land.
Help the poor.
Thou shalt not kill.
Thou shalt not steal.
Thou shalt not see.
Thou shalt not speak.
Thou shalt not bear witness, neither to the Carabinieri in Capalbio nor the Delegate of Orbetello.

Today there's a series of trails from Vulci to Lake Bolsena (and of course, the woods of Lamone) called the "Sentiero dei Briganti". Suitable for on foot, on horseback, by bike. Signs along the way describe the various episodes and stories, plus the local nature and sites of cultural interest.