Ben Chavis, the last of the Wilmington 10 defendants, was freed on parole yesterday and returned to Washington.

The 31-year-old field organizer for the United Church of Christ's Commission for Racial Justice here, served more than four years in prison after being convicted on conspiracy and arson charges in the burning of a grocery store in Wilmington, N.C., in 1971.

The case gained wide attention after key witnesses in the case changed testimony, but efforts to gain retrial were rejected. Chavis and his group were referred to as American political prisoners by Amnesty International, and Soviet officials cited the case as an example of U.S. injustice.

A year ago, the Justice Department filed an unprecedented brief asking a federal judge to overturn the 1972 state court convictions. The judge refused and the defendants are now appealing to the 4th U.S. Circuit Court of Appeals in Richmond.

In a statement yesterday, the Rev. Avery D. Post, president of the United Church of Christ in New York, said the church "still has the task of vidicating Mr. Chavis and the others of the Wilmington 10."

James Woodard, chairman of the North Carolina Parole Commission, said in a phone interview from Raleigh yesterday that Chavis became eligible for parole when Gov. Jim Hunt reduced his 17-year minimum sentence by three months.

Woodard noted that Chavis has been attending Duke University divinity school on a "study release" program and has been imprisoned only at night.

Under an interstate compact, District of Columbia authorities will supervise Chavis' parole, he added.

Hunt said he released Chavis two weeks earlier "because of his excellent record in prison, including straight A's in ministerial school at Duke University, and to permit him to be home with his family at Christmas."

Chavis told supporters yesteday he would continue to seek to prove his innocence and to fight for civil rights.

"The quest for freedom is a long struggle," he said. "We're going to march again and we're going to keep on struggling until freedom is realized."

He previously had said he would refuse parole and would settle only for a pardon. Yesterday, though, he said "I've changed my mind . . . because I feel I can do more for the civil rights movement outside prison."

The racial controversy that became the Wilmington 10 case began in late 1970, when black students at the high school there charged they were being discriminated against. Chavis went to Wilmington at the request of a black minister in January 1971.

The next month, violence broke out and two persons, one black and one white, were killed. White-owned Mike's Grocery was burned and Allen Hall was soon charged with arson.

Hall later implicated Chavis, eight other black men and a white woman, Ann Sheppard Turner. After a mistrial in June 1972, all 10 defendants were convicted and sentenced to long jail terms.

State appeals courts and the U.S. Supreme Court turned down appeals. Then, in August 1976, Hall changed his testimony and two other key prosecution witnesses also later changed their stories. This set off the latest round of appeals.

In the extraordinary Justice Department brief, it was argued that the defendants' constitutional rights had been violated because the prosecutor and judge had suppressed a statement raising doubts about Hall's testimony.

The Justice Department's "friend of the court" brief said "since there is a reasonable likelihood that the jury's verdict might have been different" if the statement had been turned over to the defense "one would conclude that the trial was imbued with a fundamental unfairness and was in violation of the due process clause of the 5th Amendment."