Historian George Horse Capture is seen in his Great Falls, Mont., home. Native American activist, curator and professor George Horse Capture has died iApril 16. He was 75. (Larry Beckner/AP)

When Native American activists from around the United States took over Alcatraz in 1969, George P. Horse Capture was a steel inspector for the California Department of Water Resources — a young man on his way to a solid career and ever further away from any sense of pride in his Montana reservation roots.

“I was very happy climbing that white mountain of success,” he once said. “But then I looked down over the top, and there was nothing there.”

The solution was to switch mountains. Joining the protesters for short periods over their 19-month stay, Mr. Horse Capture went on to become a passionate advocate for Native American culture and a museum curator who helped give his people an unprecedented voice in how their heritage would be presented and their artifacts displayed.

“He was profoundly important in contemporary American Indian history,” said Herman Viola, a longtime friend and curator emeritus of the Smithsonian’s National Museum of the American Indian in Washington.

Mr. Horse Capture, 75, died April 16 of kidney failure at his home in Great Falls, Mont., a family spokesman said. He was buried at Fort Belknap Agency Cemetery, on the reservation where he spent his early years. His tribe was the A’aninin, more commonly known as the Gros Ventre.

For Mr. Horse Capture, the explosion of Native American pride at the empty prison island in San Francisco Bay changed everything — including his name. Before Alcatraz, his last name was Capture — an adjustment his father had made to afford his children an easier time off the reservation.

Mr. Horse Capture also changed his career path. In 1974, he received a bachelor’s degree in anthropology from the University of California at Berkeley and, five years later, a master’s in history from Montana State University. The next year he joined the Plains Indian Museum of the Buffalo Bill Historical Center in Cody, Wyo., becoming one of the first Native American curators in the country.

“He was a legend as a fellow museum professional,” said Rick West, the founding director of the National Museum of the American Indian. “He had a deep commitment to the contemporary Indian community. Before the last 20 years or so, native people were rarely consulted about material in museums and had a very tortured relationship with them. All of that got turned around during the era when George was active.”

In Cody, Mr. Horse Capture placed certain sacred artifacts in a room where only tribal elders or ceremonial leaders were permitted.

“He even installed a device that shut off the alarms so they could smoke or make a smudge while praying,” Viola said in his eulogy at Mr. Horse Capture’s funeral.

One day a Catholic priest insisted he be admitted.

“For God’s sake, I’m a priest,” he said. “I want to go in there because there is sacred material.”

“I’m sorry,” Mr. Horse Capture said. “It’s not an exhibit area.”

“I’m a priest,” he said again.

“Wrong denomination,” Mr. Horse Capture replied.

In 1994, he moved to Washington, where he helped launch the National Museum of the American Indian.

In a congratulatory letter to the staff, he urged employees to find inspiration in “the tribes that came from everywhere in unprecedented numbers” to take part in the museum’s dedication. “I have never seen such a thing before and they made me feel proud to be an Indian. . . . Now the buffalo has his nose firmly in the tipi. Before this moment, we didn’t even have a tipi. Celebrate it.”

Over the next 10 years, he held several high-level positions at the museum, taking firm stands on repatriating human remains and various artifacts to their tribes of origin. After his retirement, he consulted with various institutions and put together an archive on his tribe.

Born on the impoverished Fort Belknap reservation on Oct. 20, 1937, George Paul Horse Capture was also known as “Nay Gyagya Nee,” or “spotted otter.” After high school and four years in the Navy, he enrolled in a Bureau of Indian Affairs relocation program and was sent to welding school in Los Angeles.

Survivors include his wife, KayKarol Horse Capture; four children; and many grandchildren and great-grandchildren.

Son Joseph Horse Capture is a museum curator specializing in Native American art. This month, he is leaving the Minneapolis Institute of Arts for the National Museum of the American Indian.

— Los Angeles Times