WASHINGTON >> Bill Richardson, a two-term Democratic governor of New Mexico and an American ambassador to the United Nations who dedicated his post-political career to working to secure the release of Americans detained by foreign adversaries, has died. He was 75.

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

“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,” said Mickey Bergman, the center’s vice president. “There was no person that Gov. 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.”

Speaking to reporters in Florida on Saturday, President Joe Biden called Richardson a “good friend.”

Before his election in 2002 as governor, Richardson was U.S. envoy to the United Nations and energy secretary under President Bill Clinton and served 14 years as a congressman representing northern New Mexico.

But he also forged an identity as an unofficial diplomatic troubleshooter. He traveled the globe negotiating the release of hostages and American servicemen from North Korea, Iraq, Cuba and Sudan and bargained with a who’s who of America’s adversaries, including Iraqi dictator Saddam Hussein. It was a role Richardson relished, once describing himself as “the informal undersecretary for thugs.”

“I believe that we have to engage our adversaries no matter how different our philosophies are,” Richardson once said. “The way you deal with issues that divide nations is through humanitarian efforts before political differences. I think that is fundamental.”

He helped secure the 2021 release of American journalist Danny Fenster from a Myanmar prison and this year negotiated the freedom of Taylor Dudley, who crossed the border from Poland into Russia. He met with Russian government officials in the months before the release last year of Marine veteran Trevor Reed in a prisoner swap and also worked on the cases of Brittney Griner, the WNBA star freed by Moscow last year, and Michael White, a Navy veteran released by Iran in 2020.

Roger Carstens, the U.S. government’s chief hostage negotiator, described Richardson as “a friend and partner in bringing wrongfully detained Americans and hostages home.” and said in a statement Saturday that he would “miss his wise counsel and friendship.”

Armed with a golden resume and wealth of experience in foreign and domestic affairs, Richardson sought the 2008 Democratic nomination for president in hopes of becoming the nation’s first Hispanic president. He dropped out of the race after lackluster finishes in the Iowa caucuses and New Hampshire primary.

Richardson was the nation’s only Hispanic governor during his two terms, calling it “the best job I ever had.”

“It’s the most fun. You can get the most done. You set the agenda,” Richardson said.

As governor, Richardson signed legislation in 2009 that repealed the death penalty. He called it the “most difficult decision in my political life” because he previously had supported capital punishment. Other accomplishments included $50,000-a-year minimum salaries for the most qualified teachers in New Mexico and an increase in the state minimum wage.

U.S. Sen. Ben Ray Lujan, D-N.M., called Richardson a “giant in public service and government.”

“In his post-government career, he was trusted to handle some of the most sensitive diplomatic crises, and he did so with great success. Here in New Mexico, we will always remember him as our governor. He never stopped fighting for the state he called home,” Lujan said in a statement.

Some of his most prominent global work began in December 1994, when he was visiting North Korean nuclear sites and word came that an American helicopter pilot had been downed and his co-pilot killed.

The Clinton White House enlisted Richardson’s help and, after days of tough negotiations, the then-congressman accompanied the remains of Chief Warrant Officer David Hilemon while paving the way for Chief Warrant Officer Bobby Hall to return home.

The following year, and after a personal appeal from Richardson, Saddam Hussein freed two Americans who had been imprisoned for four months, charged with illegally crossing into Iraq from Kuwait.

Richardson continued his freelance diplomacy even while serving as governor. He had barely started his first term as governor when he met with two North Korean envoys in Santa Fe. He traveled to North Korea in 2007 to recover remains of American servicemen killed in the Korean War.

In 2006, he persuaded Sudanese President Omar al-Bashir to free Pulitzer Prize-winning American journalist Paul Salopek.

In an interview with The Associated Press in August, Richardson said he was proud of the work he had done to free dozens of people over the years and of his advocacy for the Navajo Nation.

Richardson and former Navajo Nation President Peterson Zah created a fund to offer supplies and equipment to the Navajo Nation to fight the COVID-19 pandemic, providing personal protective equipment, food, water and hundreds of pairs of shoes to Navajo students in the state.

Richardson transformed the political landscape in New Mexico. He raised and spent record amounts on his campaigns, bringing Washington-style politics to an easygoing western state with a part-time Legislature.

Lawmakers, both Republicans and Democrats, complained Richardson threatened retribution against opponents. Former Democratic state Sen. Tim Jennings of Roswell once said Richardson was “beating people over the head” in his dealings with lobbyists on a health care issue. Richardson dismissed criticisms of his administrative style.

“Admittedly, I am aggressive. I use the bully pulpit of the governorship,” Richardson said. “But I don’t threaten retribution. They say I am a vindictive person. I just don’t believe that.”

Longtime friends and supporters attributed Richardson’s success partly to his relentlessness. Bob Gallagher, who headed the New Mexico Oil and Gas Association, said if Richardson wanted something done then “expect him to have a shotgun at the end of the hallway. Or a ramrod.”

In a statement, New Mexico Gov. Michelle Lujan Grisham, a Democrat, described Richardson as a visionary who saw New Mexico’s potential before others did. “New Mexico, our country, and, frankly, the entire world lost a champion today. Bill Richardson was a titan among us, fighting for the little guy, world peace, and everything in between.”

After dropping out of the 2008 presidential race, Richardson endorsed Barack Obama over Hillary Clinton despite Richardson’s longstanding friendship with the Clintons.

Obama later nominated Richardson as secretary of commerce. Richardson withdrew in early 2009 because of a federal investigation into an alleged pay-to-play scheme involving his administration in New Mexico. The investigation ended without charges against Richardson and his former top aides.

Richardson had a troubled tenure as energy secretary because of a scandal over missing computer equipment with nuclear weapons secrets at Los Alamos National Laboratory and the government’s investigation and prosecution of former nuclear weapons scientist Wen Ho Lee.

Richardson approved Lee’s firing at Los Alamos in 1999. Lee spent nine months in solitary confinement, charged with 59 counts of mishandling sensitive information. He later pleaded guilty to one count of mishandling computer files and was released with the apology of a federal judge.

William Blaine Richardson was born in Pasadena, California, but grew up in Mexico City with a Mexican mother and an American father who was a U.S. bank executive.

He attended prep school in Massachusetts and was a star baseball player. He went to Tufts University and its graduate school in international relations, earning a master’s degree in international affairs.

Richardson moved to New Mexico in 1978 after working as a Capitol Hill staffer. He wanted to run for political office and said New Mexico, with its Hispanic roots, seemed like a good place. He campaigned for Congress just two years later — his only losing race.

In 1982, he won a new congressional seat from northern New Mexico that the state picked up in reapportionment. He resigned from Congress in 1997 to join the Clinton administration as U.N. ambassador and became secretary of energy in 1998, holding the post until the end of the Clinton presidency.

Former Associated Press writer Barry Massey contributed significant biographical material to this obituary.