Elders from the Pine Ridge Indian Reservation came. Lawyers from across the country came. Author William Styron was there. So was his wife, Rose Styron, a board member of Amnesty International. The guest of honor at the reception given by 10 members of Congress was Peter Matthiessen, the author of "In The Spirit of Crazy Horse."

But actually there was a spiritual guest of honor who haunted the words and speeches of the group gathered in the Longworth Building last night. That was Leonard Peltier, the subject of Matthiessen's book, a 38-year-old Indian activist convicted of killing two FBI agents at Pine Ridge, S.D., in 1975 and now serving two consecutive life terms in a federal prison.

Peltier's lawyers and supporters, citing federal documents they obtained, say the FBI tampered with evidence during the trial and used "coercive tactics" to gain Peltier's conviction. His lawyers maintain their client's constitutional rights have been violated and that he deserves a new trial, something they have had no success in obtaining so far.

"We'd like to get him a new trial," said lawyer Bruce Ellison of Rapid City, S.D., "but we'd also like to educate the American people about the injustices and abuses of intelligence services."

Matthiessen's book is about Peltier's trial and imprisonment. "It's a very long book," he told almost 200 guests who crowded into the hearing room for the reception. "But I don't think I could have left anything out. It's a very long, very ugly story."

"I'm mainly here because I'm a friend of Peter's," said William Styron, "and I'm a supporter of his work with Indians and his point of view." Styron was also scheduled to attend a party later last night for the Virginia Center for the Creative Arts. "I'm sort of double-barreled," he said with a smile.

"Glad to have been here," Styron said, shaking hands with Lewis Gurwitz, one of Peltier's lawyers from Cambridge, Mass. "Will do anything to help the cause."

Susanna Styron, a filmmaker and the author's daughter, became involved with efforts on Peltier's behalf as part of a group of five who "congregated here trying to get last-minute clemency for Peltier during the last days of the Carter administration," she said. "Obviously, we didn't make it."

Matthiessen got onto the story while investigating transgressions of Indian land all over the country. "I didn't want to do it," he said of his book. "I'm not a political writer. But I knew more and more about it and I couldn't find anyone else to write it. I don't think it's literary. It's written for the Indian people. I don't think of it as one of my books. I didn't want to have my picture on the book. I wanted it just to be Indian voices.

"I think Peltier is not getting justice in the courts," he continued. "So that's why we're here--to get attention from Congress." Supporters have asked Congress for a hearing on the matter.

Matthiessen was one of several people who met earlier yesterday with Rep. Don Edwards (D-Calif.), chairman of the House Judiciary subcommittee on civil and constitutional rights.

Peltier is in federal prison in Marion, Ill. "He really has become more and more of a spiritual leader than before," said John Privitera, a local lawyer who is helping on the Peltier case. "Many, many people on Indian reservations are convinced of his innocence. Some Indians think of him as a prisoner of an overt war between the federal authorities and traditional people . . . His advice is still sought. A lot of people go to Marion to visit him."