It's a quest that led employees to engage fraud, and ultimately led to WaMu's failure in September of 2008, a Senate subcommittee alleges.

Along the way, the thrift infected the secondary mortgage market with billions of dollars in bad loans.

Those are the findings of year and a half long investigation by the Senate Permanent Subcommittee on Investigations.

The panel is holding the first of four hearings Tuesday on the role high risk mortgages played in the financial crisis.

"Using a toxic mix of high risk lending, lax controls and destructive compensation practices, Washington Mutual flooded the market with shoddy loans and securities that went bad," the subcomittee's Chairman Carl Levin (D-Mich), said in a statement.

Levin said his subcommittee looked at the Seattle-based thrift as a case study.

He described it as the story of a 100 year old traditional lender that turned away from safer lending practices to pursue the higher profits reaped from selling high risk mortgages to Wall Street firms.

As it did, the thrift failed repeatedly to bring the hammer down on fraudulent practices rampant in some of its most profitable mortgage centers.

Starting in 2003 WaMu began increasing the production of subprime loans.

At the time, Wall Street firms were buying these mortgages, bundling them together, slicing them into pieces and selling them to yield-hungry investors in a process known as securitization.

Despite the underlying nature of the loans, the securitized products often received triple A ratings from credit rating agencies.