Bill Richardson, who served as governor of New Mexico, and as both the U.S. ambassador to the United Nations and Energy secretary during the Clinton administration, has died at age 75.

The Richardson Center for Global Engagement, which he founded, said in a statement Saturday that he died in his sleep at his home in Chatham, Massachusetts.

Mickey Bergman, vice president of the Richardson Center, said:

Governor Richardson passed away peacefully in his sleep last night. He lived his entire life in the service of others — including both his time in government and his subsequent career helping to free people held hostage or wrongfully detained abroad. There was no person that Governor Richardson would not speak with if it held the promise of returning a person to freedom. The world has lost a champion for those held unjustly abroad and I have lost a mentor and a dear friend.

Richardson served in several roles during his time in government---and he even made a short-lived run for president in 2008:

The son of a Mexican mother and an American father, Richardson served from 1982 to 1996 as a Democratic member of the U.S. House of Representatives, then as U.S. ambassador to the United Nations and energy secretary, both under President Bill Clinton. Richardson was elected as governor of New Mexico, serving from 2003 to 2011.

Richardson, while serving as New Mexico governor, sought the 2008 Democratic presidential nomination but dropped out after disappointing finishes in key early voting contests in New Hampshire and Iowa.

But most people are familiar with Richardson for his independent role in trying to help Americans being held by foreign (often authoritarian) governments gain release. He said during an interview on a Foreign Policy magazine podcast in 2018:

The first rule of negotiating, with me, is you've got to relate to your adversary personally. You have to respect them. You've gotta know what ... makes them tick. You've gotta let the other side save face and find some ways that they get some credit, that they're getting something out of the negotiation, when in effect the only thing may be praise for a humanitarian gesture.

The Richardson Center's statement continued by pointing out that "right now our focus is on supporting his family, including his wife Barbara of over 50 years, who was with him when he passed. We will share further information as it becomes available."