[Last Updated 7:24 a.m. By DEBORAH MENDEZ Associated Press, April 3, 2003]

DENVER (AP) - The slaying of American Indian Movement activist Anna Mae Pictou-Aquash has gone unsolved for nearly 30 years, frustrating local and federal investigators.

But now, with a suspect in custody, they say the pieces may be coming together.

Arlo Looking Cloud, a 49-year-old homeless man, was arrested March 27 in Denver on a warrant issued by federal authorities in South Dakota. Looking Cloud and another man are accused of shooting Pictou-Aquash during a kidnapping in December 1975 near Wanblee, S.D.

Looking Cloud pleaded innocent to first-degree murder on Monday, U.S. Attorney James McMahon said Wednesday in Sioux Falls, S.D. A judge was expected to decide Thursday whether he should be sent to South Dakota to be prosecuted.

Pictou-Aquash's frozen body was found on South Dakota's Pine Ridge reservation in February 1976. The 30-year-old woman, who had been shot in the head, had disappeared from a Denver home several months earlier.

Looking Cloud worked as a security guard at AIM events during the 1970s, said Paul DeMain, editor of the bimonthly newspaper News From Indian Country in Wisconsin who has researched the case extensively.

Police in Denver were familiar with Looking Cloud because he has been cited for several misdemeanors, including trespassing and public drinking, during the years he has lived on the city's streets.

Denver detective Abe Alonzo, who was first assigned to the Pictou-Aquash case nearly 10 years ago, said Looking Cloud was known to loiter on Colfax Avenue, one of the city's main streets.

"It was almost like it was too easy," said Alonzo, who walked up to the suspect on the street before calling uniformed officers to make the arrest.

Looking Cloud, a Lakota Indian, was arrested on a trespassing charge and later seemed surprised to learn that he was wanted in the Pictou-Aquash slaying.

"I don't think he actually thought this was happening," said Alonzo, who last had contact with Looking Cloud in January. He would not elaborate.

According to a rap sheet released by police, Looking Cloud used as many as 23 aliases over the past nine years.

The man named along with Looking Cloud in a March 20 indictment has not been taken into custody. Authorities gave no detail.

Pictou-Aquash was a member of Canada's Mi'kmaq Tribe. She was among Indian militants who occupied the village of Wounded Knee in a 71-day standoff with federal authorities in 1973. There was some speculation she was killed by AIM members because she knew some of them were government spies. Others said Pictou-Aquash was killed because she herself was an informant.

Federal authorities repeatedly have denied any involvement.