Sioux Falls, S.D. ? When machine-gun-toting American Indian Movement militants took over Wounded Knee in 1973, the eyes of the world focused on the tiny Pine Ridge reservation village and the tense 71-day standoff with federal agents.

Three years later, the body of AIM activist Anna Mae Pictou-Aquash was found on the reservation, shot once in the head and left in a ravine.

Some speculated Aquash, who participated in the standoff, was killed by AIM members because she knew some were government spies. Others said she was killed because Aquash herself was an informant.

On Tuesday, more than a quarter-century after the slaying, a trial is set to begin for one of two former AIM members indicted last year on charges of first-degree murder in Aquash’s kidnapping and death.

Arlo Looking Cloud, a homeless man who grew up on the reservation, will face jurors in Rapid City federal court.

The other man, John Graham, pleaded not guilty and remains free on bond in Canada. He told The Associated Press he would fight extradition.

Investigators have said the two men were instructed to kill Aquash, but AIM leaders have denied any involvement. Prosecutors and Looking Cloud’s lawyer would not speak publicly about the case.

One of Aquash’s daughters, Denise Maloney Pictou, said she hoped Looking Cloud’s trial led to some long-overdue answers.

“It may be the first step to closure,” she said. “I’m not going to settle that these gentlemen get put in jail. We want explanations as to why her murder wasn’t addressed.”

Both defendants, who did low-level security at AIM events in the 1970s, would face mandatory life sentences if convicted.

Anna Mae Pictou-Aquash, seen in this undated snapshot, was found dead Feb. 24, 1976, on South Dakota's Pine Ridge Indian Reservation.

AIM spokesman Vernon Bellecourt said he planned to attend the trial to determine whether the jury was unbiased and if there was enough evidence.

“No one knows who pulled the trigger, in that there is no forensic evidence other than hearsay, innuendo, conjecture and gossip,” Bellecourt said in a telephone interview.

A member of Canada’s Mi’kmaq Tribe, Aquash was killed at a time when tensions between AIM members and government-backed factions ended in numerous deaths on the reservation.

After the deaths of two FBI agents on the reservation in June 1975, the 30-year-old Aquash fled with several top AIM leaders. Six months later, she disappeared from a Denver home where she was staying.

Her frozen body was found early the next year on the western South Dakota reservation.

In a 2000 interview with the Canadian Broadcasting Corp., Kamook Nichols, former wife of AIM co-founder Dennis Banks, said Aquash was not a government informant, though Banks and fellow AIM leader Leonard Peltier probably believed she was.

That, according to Nichols, is likely why Aquash was allowed to flee with Nichols, Banks and Peltier after the two FBI agents were killed.

“I think that maybe they wanted to keep an eye on her,” Nichols said.

Peltier later was found guilty of killing the agents and is serving back-to-back life sentences at Leavenworth, Kan. He has maintained his innocence, but several appeals have failed to overturn the conviction.

Banks did not reply to a request for an interview, though in the past he has denied any involvement in Aquash’s death.

Paul DeMain, a journalist who has researched Aquash’s death, believes prosecutors will attempt to establish that Aquash had heard Peltier brag about killing the two agents — and might also have heard AIM leaders talk about the killing of black civil rights worker Ray Robinson, who was killed during the Wounded Knee standoff.

“Motives that could be established at trial were that (Aquash) knew Leonard Peltier had shot the agents he was convicted of killing, and that she was probably knowledgeable about the death of … Robinson inside Wounded Knee in 1973 and the involvement of several AIM leadership people in that death,” DeMain said.

Peltier has sued DeMain for libel, partly because of the accusation.

Retired FBI agent Don Wiley, of Rapid City, said the case went unsolved for so long in part because of resistance to the agency on the reservation.

“I think it was just that people were not cooperative with the bureau’s investigation,” Wiley said. “You can imagine. Put yourself in a law enforcement officer’s shoes and you’re going around asking questions about a case that happened on Pine Ridge.”