The collapse is now the subject of a class-action lawsuit from the company's bondholders.
Leppert, who was elected in 2007, joined the board of the Seattle-based bank in 2005.
The Dallas Morning News reports the lawsuit claims that's the year WaMu allegedly loosened its cautious lending practices in pursuit of higher profits.
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J.P. Morgan Chase & Co. acquired the bank's assets for $1.9 billion in September along with its future liabilities.
Leppert declined requests for comment and referred questions to the company.
Regulatory documents show Leppert received total compensation valued at more than $320,000 from WaMu in 2006 and 2007.