A Washington psychiatrist, called by attorneys for accused slayer Edward Thomas Mann, testified yesterday that Mann is suffering from a "major mental psychotic disorder" and is not competent to stand trial.

Dr. Thomas Goldman added one more voice to the battle of experts that has been waged in Montgomery County Circuit Court, where Judge William C. Miller is trying to determine whether Mann can stand trial for his alleged crimes last year at the IBM building in Bethesda. Mann's bizarre actions since his arrest and the diagnosis that he suffers from paranoia have called Mann's competency into question.

Since the hearings began last month, four psychiatrists called by the prosecution have testified that Mann is competent to stand trial, while six experts called by the defense have said that he is not.

The testimony ended yesterday, and Miller said he will rule today whether Mann can now stand trial on charges that he killed three people during last May's siege at IBM.

As the testimony ended, Miller asked Mann if he had any comments. "The state did a great job," Mann replied, complimenting the prosecutors, as he has throughout the hearing. Mann has said repeatedly that he wants to plead guilty and has refused to cooperate with lawyers appointed to represent him.

If Mann is found incompetent, he would return to the Clifton T. Perkins State Hospital where he has been since an alleged suicide attempt last month.

He would periodically come up for reevaluations to determine whether his condition had improved enough to allow him to stand trial.

The charges would remain against him for at least 10 years, after which a judge could dismiss them. Mann, however, would not be released from the hospital unless a judge found that he was no longer a danger to himself or others.