A Silver Spring woman who set out to kill herself but killed her husband instead has been set free after 13 months in prison.

Margaret Pratt wanted to kill herself in 1976, her attorney said, but killed her husband William first because she thought he could not live without her. She turned herself in the next day.

She pleaded insanity before a jury in 1977, but was found guilty of second-degree murder. After an appeals court struck down crucial testimony in the first trial, prosecutors told a Montgomery Circuit Court judge Monday, that they could no longer prove that she was sane at the time of the murder.

The Maryland Court of Special Appeals ruled that prosecutors had "interfered" with Pratt's attorney-client privilege because the state had used as a witness the same psychiatrist that Pratt's defense attorney had consulted at one point before the trial.

Deputy State's Attorney Timothy Clarke said he decided to use the psychiatrist, Dr. Brian Crowley, because the defense had decided against using Crowley as one of its witnesses.

But the Special Court of Appeals ruled that "the defendant needs to be able to confide in her attorney and any . . . consultant [employed by the defense]. If the defendant knew what she told to [the consulant] was going to be available to the state, that would have a detrimental effect on the defense," Clarke said.

The state would not have been able to use Crowley's crucial testimony that Pratt was sane at the time the crime was committed during a second trial.

"I come to the conclusion that we were going to lose the case. So under those circumstances, why waste the taxpayer's money" on a new trial? Clarke asked.

Judge David L. Cahoon found that Pratt was responsible for her husband's murder but accepted the defense's contention that she was insane at the time of the crime and therefore not guilty.

Judge Cahoon said he released Pratt on the basis of psychiatrist Dr. Gerald Polin's evaluation that Pratt no longer poses a threat to herself or to others.

On October 22, 1976, Pratt contemplated killing herself, according to her defense attorney Robert Heeney, with a 32 automatic pistol in the Silver Spring apartment she then was sharing with her husband. Instead, she killed her husband of 36 years who was at the time overweight, suffering from diabetes and had lost his vision in one eye.