Indigenous activist Leonard Peltier, who has spent most of his life in prison since being convicted of murdering two FBI agents in South Dakota in 1975, has been denied parole.

The U.S. Parole Board announced Tuesday that he would not be eligible for a parole hearing again until June 2026. Peltier is serving a life sentence for killing the agents during a standoff on the Pine Ridge Indian Reservation in South Dakota. He was convicted in 1977.

His lawyer, Kevin Sharp, a former federal judge, announced that he would appeal. He had argued that Peltier had been wrongfully convicted and that the 79-year-old's health was failing.

“This decision is a missed opportunity for the United States to finally acknowledge the FBI's misconduct and send a message to Native Americans about the impact of federal government actions and policies in the 1970s,” he said in a statement.

The fight for Peltier's freedom is closely linked to the indigenous rights movement. Almost half a century later, his name is still a rallying cry and T-shirts bearing the slogan “Free Peltier” are being sold online.

“The way they treated Leonard is the way they have historically treated Indigenous peoples across the country,” said Nick Tilsen, president and CEO of the NDN Collective, an advocacy group led by Indigenous peoples. “That's why Indigenous peoples and oppressed people all over the world see a little bit of ourselves in Leonard Peltier. Although today is a sad day, we will not stop fighting.”

The FBI and its current and former agents deny the claims of innocence.

“They were down, they were wounded, they were helpless and he shot them at point blank range,” said Mike Clark, president of the FBI's Society of Former Special Agents. “It's a heinous crime.”

FBI Director Christopher Wray said in a statement that “justice continues to prevail.” And Natalie Bara, president of the FBI Agents Association, described Peltier in a statement as an “unrepentant killer.”

“We believe this decision brings justice to our fallen colleagues and their families,” the statement said.

Peltier was a member of the Turtle Mountain Band of Chippewa in North Dakota and was involved in the American Indian movement, which began as a local organization in Minneapolis in the 1960s to address issues of police brutality and discrimination against Native Americans and quickly grew into a national force.

Tilsen, a citizen of the Oglala Lakota Nation, credits AIM and others with most of the rights Native Americans have today, including religious freedom and the ability to operate casinos and tribal colleges and to contract with the government for oversight of schools and other services.

AIM made headlines in 1973 when it captured the village of Wounded Knee on the Pine Ridge Reservation, leading to a 71-day standoff with federal agents. Tensions between AIM and the government remained high for years.

On June 26, 1975, agents arrived at Pine Ridge to execute arrest warrants amid disputes over Native American treaty rights and self-determination.

Agents Jack Coler and Ronald Williams were wounded in a shootout and shot in the head at close range, Wray said. AIM member Joseph Stuntz was also killed in the shootout. The Justice Department concluded that Stuntz was killed by a police sniper.

Two other AIM members, Robert Robideau and Dino Butler, were acquitted of killing Coler and Williams.

After fleeing to Canada and being extradited to the United States, Peltier was sentenced to life imprisonment in 1977 for two counts of premeditated murder, despite his defense claiming that the evidence against him had been fabricated.

Amnesty International is also among his supporters. In a statement, it said his imprisonment was a “tragedy for human rights”.

His final parole hearing was held in June at a maximum-security Florida prison, part of the Coleman Federal Correctional Complex. Afterward, his lawyer, Sharp, said the board was required by law to “look forward” and focus on questions such as whether he is likely to commit another crime if released.

Relatives of the two agents have long called for Peltier to remain behind bars. In a 2022 letter to Wray, Coler's son, Ronald Coler, said the campaign for Peltier's release had been painful for the family.

“My family has not only suffered the loss of my father, we have also had to endure the insult of Peltier becoming a popular cause and figurehead of Hollywood, the music industry, politicians and well-meaning activists who assume or believe he is being unfairly punished,” he wrote. “Peltier allows himself to be celebrated in this way. He knows his guilt.”

Parole was also denied at a hearing in 2009, and then-President Barack Obama denied a request for clemency in 2017. Another request for clemency is pending before President Joe Biden.

— By HEATHER HOLLINGSWORTH, Associated Press. John Hanna contributed to this report from Topeka, Kansas. Hollingsworth reported from Mission, Kansas.