Jack Lew had major role at Citigroup when it nearly imploded

The Washington Post reports on Jacob Lew:

In early 2008, he became a top executive in the Citigroup unit that housed many of the bank’s riskiest operations, including its hedge funds and private equity investments. Massive losses in that unit helped drive Citigroup into the arms of the federal government, which bailed out the bank with $45 billion in taxpayer money that year.

Few people are less deserving of being the Secretary of the Treasury than Jacob Lew. Why isn't he in jail????