WASHINGTON – Bill Richardson – a 2008 presidential candidate, former New Mexico governor, former secretary of energy and U.N. ambassador under the Clinton administration and congressman – died Friday in his sleep at his summer home in Chatham, Massachusetts. He was 75 years old.

Amid his career as a politician and diplomat, Richardson became known for his role in freeing hostages and other wrongly detained Americans. President Bill Clinton helped give him the nickname “undersecretary for thugs.”

Mickey Bergman, vice president of the Richardson Center for Global Engagement, commented that “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,” Bergman said. “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.”

In recent years, he spent much of his time as a private diplomat representing the growing number of American families seeking to free their loved ones unjustly detained abroad. He filled a whole biography with tales of his high-stakes meetings with tribal leaders and tyrants, writing about brokering deals with Fidel, Saddam, Hugo and “a Kim or two.”

More from USA TODAY: Bill Richardson’s endless push to free Americans detained abroad

Neda Sharghi, chair of the nonprofit Bring Our Families Home Campaign, was one of the many people who sought Richardson’s counsel. Her brother, Emad Shargi, who spells his surname differently, is an American businessman who has been held in Iran since 2015, and is the subject of discussions of a possible prisoner swap. “On behalf of the countless families that Governor Richardson and his Center have helped, I wanted to express our profound feeling of loss at his passing,” Sharghi said. “Governor Richardson has been a fierce advocate for human rights and the effort to bring home people unjustly held overseas.”

“Governor Richardson was a mentor of mine and he will be missed by many, including and especially the countless families he helped over the years. My prayers are with Barbara and his family,” said Jon Franks, who worked with Richardson to secure the release of Americans detained overseas including Trevor Reed, a former Marine who was detained in Russia in 2019. Barbara is Richardson’s wife.

‘The governor’: Bill Richardson and New Mexico

Even at age 75, Bill Richardson’s staff and many others referred to him as “the Governor,” a title he had not held in more than a decade.

U.S. Rep. Gabe Vasquez, D-NM, called Richardson “a titan in New Mexico and abroad” on X, the platform formerly known as Twitter.

“I mourn the passing of this New Mexico legend, one of the most powerful Hispanics in politics that this nation has seen,” Vasquez said. “Today, we reflect on his decades of service and for always proudly representing New Mexico.”

Richardson continued to live in New Mexico, driving an aging Jeep Wrangler to a modest office in downtown Santa Fe where he ran the Richardson Center’s efforts, talking by phone to contacts across the globe.

Richardson’s role in deal to free Brittney Griner

Richardson contributed to efforts to broker a deal for the release of Brittney Griner, the WNBA star who spent 10 months in a Russian prison after she was detained for allegedly possessing cannabis oil in her luggage. Griner was eventually exchanged for convicted Russian arms dealer Viktor Bout. The exchange illuminated the shadowy but central role Richardson could play in such deals.

Only the U.S. president can authorize such high-profile prisoner swaps, but after Griner’s release in December 2022, her family issued a public “special thank you” to Richardson.

Griner’s agent, Lindsay Kagawa Colas, previously told USA TODAY, referring to Richardson and his director and second-in-command at the Richardson Center, Mickey Bergman, “We did not make any major moves without consulting them.” Griner’s wife or representatives “spoke with Mickey on almost a daily basis.”

This article originally appeared on USA TODAY: Bill Richardson, a former New Mexico governor and diplomat, dead at 75