"He was literally a one-man financial crime wave," Rice said. "He kept putting himself out there as a lawyer. He kept engaging in victims, taking their money and doing it just because he could and because he wanted to pay for his lifestyle."
(Read more: How thieves steal billions in fake tax refunds)
According to authorities, Kalpakis kept presenting himself as an attorney in real estate deals, forging mortgage documents to obtain loans and stealing money from client escrow accounts—just as he had been caught doing in 2005.
In one such case, he forged the deeds to four homes he did not own and was not authorized to sell. He then sold all four as investment properties to a local resident.
Authorities told CNBC that the victim, who trusted Kalpakis as a friend and member of the community, saw only one of the four properties before buying them.
Bette Kalpakis, now his ex-wife, was also a victim. According to the charges, Kalpakis conned her out of $402,152 by forging power of attorney on a mortgage loan with JPMorgan Chase for their Old Westbury residence, whose deed was in her name. He got the loan without her knowledge, then pocketed the money.
Sources also told CNBC that Kalpakis even victimized a girlfriend in a bogus business deal.
(Read more: 'Pot mom' admits running a weed warehouse)
Kalpakis told CNBC that he regretted everything he has done and intends to pay back everything.
"I know it's crazy and people will roll their eyes when I say I didn't attempt to steal money from anyone, but that wasn't my intention," he said. "I want to show that I'm truly sorry and regret everything that I've done in my life. I don't want to hide from what I've done; I don't want to run from what I've done. I want to take responsibility. ... And if I have to work the rest of my life to make things right, I will do that."
Kalpakis, who pleaded guilty to grand larceny in the first degree and second degree, is scheduled to be sentenced Dec. 3 in Nassau County.
—By CNBC's Andrea Day; follow her on Twitter
—By CNBC's Valerie Patriarca; follow her on Twitter