The arrests came after the victim managed to escape a home in SoHo, one of the wealthiest neighbourhoods in New York, where he was allegedly tortured and bound for nearly three weeks.
According to police, Mr Duplessie is the business partner of John Woeltz, 37, who was arrested on Friday.
Mr Woeltz is a crypto investor from Kentucky and has been renting the SoHo home – where the assaults allegedly occurred – for between $30,000 (£22,000) and $40,000 per month, according to the BBC’s US partner CBS News.
Investigators in the case also arrested a woman on Friday, but prosecutors have declined to press charges against her.
The alleged victim, who has not been named publicly, told police he came to New York from Italy on 6 May.
He alleged that upon arriving at the suspect’s house, Mr Woeltz took his passport and held him captive for 17 days.
Police say he had a gun pointed at his head, was struck with the gun, and had threats made against his family as his attackers demanded he reveal his password. He was also allegedly forced to smoke crack cocaine.
The 28-year-old Italian national says he escaped on Friday morning, bloodied and barefoot, after agreeing to give the men his password.
When they went to get his laptop, the alleged victim says he fled the eight-bedroom townhouse.
He reported the attack and was taken to hospital for treatment, say authorities.
A police search of the home found several Polaroid photos of the victim being tied up and tortured, as well as firearms and drugs, police say.
In a separate case in France, police have arrested more than 20 people following a number of kidnapping plots targeting crypto entrepreneurs and their families.
Authorities said the arrests were in connection with investigations into a recent abduction attempt in Nantes and the attempted kidnapping of a woman and child in Paris in May.
David Seltzer, a criminal defence attorney who specializes in cyber-crime, said such cases are all too common.
“It’s becoming a thing because people think it’s an easy way to get cash,” he told the BBC’s US partner CBS.
“Instead of robbing a bank, they can kidnap someone and get access to their Bitcoin wallet or crypto wallet.”
