Who could be better than your best friend's husband to be your financial advisor?

It could be the biggest mistake of your life.

Carrie Brown of Memphis, Tenn., knows from experience. Carrie's lifelong friend, Tina Caronna was married to Joe Caronna, a guy with a head for numbers and a gift of gab that led Joe and Tina's family and friends like Carrie to buy insurance and annuities from him.

They figured Joe would do right by them. The Caronnas were moving up in the world, buying a bigger house in an upscale neighborhood and amassing a fantastic collection of sports cars.

There was only one problem: Joe's increasingly deeper pockets were being lined with his clients' money, in some cases, their life savings. In 2013, Caronna was sentenced to 85 months in federal prison for stealing nearly $700,000 from 18 clients. Caronna is also serving a life sentence for the murder of his wife Tina.

How Caronna's crimes are intertwined will be revealed in the season premiere of "American Greed," on Wednesday, March 19.

According to CNBC's Suze Orman, the disaster that transformed Caronna's clients into victims might have been prevented if they had seen the red flags that are signs of a crooked financial advisor.

"The first thing you have to understand is be very careful when a family member or a friend says, this person is great. That's my first warning sign, believe it or not."

Orman cautions to never write a check made out directly to a financial advisor or to a firm that only has one or two offices. "You only want to write a check to a major firm or bank that has 20 or 30 other offices throughout the U.S. If your particular office goes under, you know you have many other offices you can go to."

While most financial advisors are honest, Orman hears horror stories about the thieves all the time.

"An older woman came to me directly. Her husband had just died. The insurance agent who had sold him a life policy now shows up at her house to express his condolences and brought checks from the policy, about $500,000. And he says, 'If you just sign on the back, I'll go and get the money and put it in your account.' And she signed on the back, he cashed it and she never saw him again."

"Be careful, people. Be careful."

But what if it's too late?

"If you think you've been ripped off by your broker, you need to contact FINRA," said CNBC's personal finance correspondent Sharon Epperson. "That is the agency that regulates brokers. Go to the Investor Complaint Center at finra.org/complaint and file your complaint."

Don't expect results immediately. "It can take a while to get your money from fraudulent financial advisors or brokers," said Epperson.

How long? Six years after the Bernie Madoff scandal, 56 percent of what investors lost in that tragedy has been recovered, with only a handful of victims being made whole again.

—By Robert Waldman, Special to CNBC.

Some people will do anything for money. All new episodes of "American Greed" return to CNBC starting Wednesdays at 9 p.m. ET.