Liuzzo, 24, stood accused of manslaughter following the death of student Johnathan Duchatellier in 2004, but he avoided prison after making a guilty plea on lesser charges.
The duo were often spotted out in London and even ran the London Marathon together in 2010.
Princess Beatrice even moved to San Francisco and then New York City to be with her boyfriend as he climbed the ranks with taxi app Uber.
British royal Princess Beatrice is dating her first serious boyfriend - an American socialite who once faced manslaughter charges following a drunken brawl.
Beatrice - who is the daughter of PRINCE ANDREW and his ex-wife Sarah Ferguson, DUCHESS OF YORK - has been spending time with New Yorker Paulo Liuzzo for several months, and went public with their romance during a recent skiing trip to Switzerland.
The insider says, "Paulo and Beatrice are very close.