"There is a possibility of a psychiatric defense being raised," Mr. Gotlin said.

Mr. Ross, who still believes that his mental illness should spare him from the death penalty, would then put on a full psychiatric defense.

He also rejected the argument that a psychiatric defense should have been presented.

But he said Mr. Ferguson had rejected them after they also insisted on a psychiatric defense.

"No one is going to force me to have a psychiatric defense."

The comment was the first to indicate the type of attack that prosecutors might mount against any psychiatric defense.

Under state law, statements to psychiatrists cannot be used unless a psychiatric defense is used.

"We indicated there was a psychiatric defense in the case," Mr. Rubin said yesterday.

Steven Reed, a spokesman for the district attorney's office, would not comment on the possibility of a psychiatric defense.

But the trial was also notable as a test case for a rare type of psychiatric defense.