A former investment manager known as Wall Street's "bad boy" was sentenced Thursday to 12 years in prison.

Ross Mandell was sentenced by Judge Paul Crotty for his conviction at trial last summer on conspiracy and securities fraud charges. The government said he defrauded U.S. and European investors of $140 million and asked that he be sent away for life.

"I'm not asking you for leniency today Judge Crotty, I'm begging you. I'm pleading with you," the former chief executive officer of Sky Capital said before the judge announced his sentence. Mandell was also ordered to forfeit $50 million. He must report to prison June 18.

"It was never my intention to cheat or steal," Mandell said during lengthy remarks to the court. "I've never taken any money from anyone sir."

Sky Capital had offices in London, New York, Florida and New Jersey. His lawyer has promised to appeal.

The trial captured the hard-partying lifestyle brokers enjoyed during the dot-com boom of the late 1990s and early 2000s. Prosecutors say Mandell treated his brokers to fast times in London, spending $1.3 million at the nicest hotels in Europe and bringing plenty of petty cash for strip clubs and prostitutes.

An exhibit introduced at trial by prosecutors showed that Mandell charged $162,000 on credit cards at adult entertainment clubs in London and New York from May 2001 through January 2006.

Prosecutors portrayed Mandell and a co-defendant who awaits sentencing as con men, saying they capitalized on the excitement over Internet tech stocks by using their broker-dealer operation to solicit private investments in startups. Prosecutors said the defendants spent some of investor money living lavishly with private jets, expensive vacations, fancy cars and flashy watches. They said the men manipulated the value of stocks they sold to investors in part by paying brokers 400 percent commissions to promote the stocks.

The scheme came to an end when one of the brokers was caught lying to an FBI undercover officer. The broker agreed to secretly tape-record conversations with Mandell.

Assistant U.S. Attorney Katherine Goldstein told jurors in closing arguments that Mandell told his brokers to target foreign investors because they didn't hang up the phone like Americans.

"They are not jaded like we are," Goldstein said Mandell told the brokers. "They are easier to convince. All you have to do is say the name Wall Street."

Mandell, who has homes in Manhattan and Boca Raton, Fla., with his wife and two young daughters, was arrested in 2009. He has said he is a recovering alcoholic, fitness maven and family man who quit the fast lifestyle of the late 1990s and early years of the new century.

He has embraced his "bad boy" image and says he overindulged in fast-lane excesses before getting sober and becoming rich.

An admitted co-conspirator who testified against Mandell at trial said that money raised from investors was spent on "strip clubs and prostitutes."