Jeremy Hobson: The government is expected to file criminal charges today against two former traders at the investment bank Credit Suisse for allegedly misstating the value of mortgage bonds back in 2008. It would be one of the first and most important criminal cases related to banks that helped cause the financial crisis.

Marketplace’s Nancy Marshall-Genzer reports.

Nancy Marshall-Genzer: It’s become a familiar accusation. That during the mortgage crisis, banks packaged shaky mortgages into securities, and sold them to investors at inflated prices.

Hillary Sale teaches law at Washington University in Saint Louis. She says traders had ample reason to push these investments.

Hillary Sale: Individuals bonuses would have been based to some extent on, actually, completion of these trades. And then there was just the incentive to get them off the books and out.

Very few people have been charged so far. And few cases have been brought. Why has it taken so long? Carl Tobias is a law professor at the University of Richmond.

Carl Tobias: There is difficulty having any kind of cooperation and of course, the government wants to be absolutely certain that it has a rock solid case.

Think of prosecutors as detectives. They have to understand these investments, sift through them, and then try to explain them to a jury. The only other time federal prosecutors argued a case like this — in 2009 — they lost. Two Bear Stearns traders were found not guilty.

In Washington, I’m Nancy Marshall-Genzer for Marketplace.