A Syosset man allegedly stole millions of dollars from senior citizens on Long Island with a Ponzi scheme, according to Nassau's district attorney.

Investigators say Matthew Eckstein, a 48-year-old financial adviser, preyed on the elderly and squandered their money.

"This defendant used that money to enrich himself, to invest in his own businesses, to help pay for the down payment of his home," said Nassau District Attorney Madeline Singas.

That home is in the Oyster Bay Cove, a luxurious private community, with a swimming pool and tennis court.

Prosecutors say he convinced one of his 14 victims to invest $385,000 by assuring her there was no risk and that her principle would be returned within two years.

When that victim started calling Eckstein asking where her money was, he allegedly stopped returning her phone calls. That's when investigators say she called the police.

Singas says many of the victims gave him their retirement savings believing they would be invested in low-risk places.

Financial planner Michael Kresh says an offer like that is a warning sign.

"No matter what you do, there's no such thing as a risk-free investment," Kresh says. "If they're going to show you or promise you something that will help you achieve your goal, they're wrong. If they use the word 'guarantee,' leave the room."

Singas also warned potential investors to be more vigilant.

"You have to be a little skeptical," she says. "You have to do your homework. You have to ask around. Make sure that someone has the financial reputation that they claim they have."