A woman who says James Earl Ray was not Martin Luther King Jr.'s assassin was committed to a state mental hospital without regard to her role as a possible witness in Ray's defense, Tennessee authorities testified yesterday.

Grace Walden Stephens has become a key figure to critics who say there was a cover-up of a conspiracy to kill the civil rights leader.

Lawyer Mark Lane charges that the House Assassinations Committee is attempting to "destroy" Stephens. As her legal guardian, Lane said yesterday he has advised Stephens not to testify before the panel.

On the day of the assassination, April 4, 1968, Stephens was a resident in the Memphis rooming house from which King was believed to have been shot.

She has said in various forums that a man she saw fleeing the bathroom in the rooming house shortly after the assassination was not Ray.

By her account, the man was older and thinner than Ray.

A few months after the assassination, she was taken by her common-law husband to a Memphis hospital, where Lane claims she was given "mind-crippling drugs." She subsequently spent 10 years in Western State Mental Hospital in Boliver, Tenn.

Lane charged that authorities in Tennessee successfully suppressed her description of the man in the Memphis rooming house, allowing Ray to be charged alone with the murder.

To refute Lane, the committee yesterday called six witnesses, including four doctors, who traced the steps that led to a legal declaration that Stephens was mentally incompetent.

All said there was no connection between the assassination and the decision to commit Stephens, now 62 and living in Memphis.

Lane, instead of allowing testimony by Stephens, said he had her prepare an affidavit that he would deliver to the committee members.

"They are biased and prejudiced and will try to destroy her as a human being," Lane said of the members.

Asked if he were risking a contempt-of-Congress citation. Lane replied: "If they say I have contempt for this committee, they are accurately assessing my feeling."