Synthetic identity fraud continues to grow in the U.S., costing billions and impacting millions.

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Synthetic identity fraud is when thieves use personal information about several people to create one identity.

"It's when someone takes one person's social security number, another person's name and address and a third person's date of birth, and combines it to create, effectively, a bionic person," said Adam Levin, chairman and founder of IDT911 and Levin also served as the director of the New Jersey Division of Consumer Affairs.

And while identity theft is hard enough to detect, Levin said synthetic identity fraud poses an even greater challenge for law enforcement since it pulls information from a bunch of people to create one identity.

In many cases, identity thieves often target the most vulnerable when creating a new identity.

"Oftentimes they use social security numbers for the dead or for children because they're pristine," Levin said.

Another target is senior citizens, where identity theft can go for years without being noticed.

"The goal of the thief is to try to leave a trail of breadcrumbs that leads somewhere, but the more hidden that somewhere is the better because it will take longer to detect the fact that there's a problem," Levin said.

Levin said crooks are using synthetic identity fraud to commit all kinds of tax and financial fraud.

Unfortunately, it can take years to repair the damage done from synthetic identity fraud.

"The longer it's allowed to percolate, the more damage that can be done, the more difficult to unravel, and the more pain that the people who are mixed  up in this go through," Levin said.

So what can you do to prevent synthetic identity fraud?

Levin said people should be doing all sorts of things to minimize the risk.

"Limiting the number of credit and debit cards you carry, securing your computer and your smartphone. Not giving information to people that you don't know, and also shredding every document you have that has sensitive information," Levin said.

He also advises people to use longer and stronger passwords and to never carry their social security cards with them. In addition, people should monitor their bank and credit card statements and request copies of their credit reports.

Some credit repair companies are trying to sell consumers Credit Profile Numbers, known as CPN's, to supposedly help people repair their bad credit history, but Levin said these substitute social security numbers are not legal and should never be bought or used.

According to a Sept. 23 ABC report, 85 percent of all identity fraud in the nation is considered synthetic identity fraud.