Please answer a question about the following article about New Haven, Connecticut:

Garry Trudeau, creator of the political Doonesbury comic strip, attended Yale University. There he met fellow student and later Green Party candidate for Congress Charles Pillsbury, a long-time New Haven resident for whom Trudeau's comic strip is named. During his college years, Pillsbury was known by the nickname "The Doones". A theory of international law, which argues for a sociological normative approach in regards to jurisprudence, is named the New Haven Approach, after the city. Connecticut US senator Richard Blumenthal is a Yale graduate, as is former Connecticut US Senator Joe Lieberman who also was a New Haven resident for many years, before moving back to his hometown of Stamford.

Which past U.S. senator had lived in New Haven and graduated from Yale?
Joe Lieberman