A woman accused of killing an expectant mother and cutting the baby from her womb told a psychiatrist that she gave birth three days before the crime, the psychiatrist testified Tuesday.

Dr. Linda McCandless, a psychiatrist who has been treating Lisa Montgomery since she was arrested in December 2004, also testified that Montgomery believed she was pregnant starting in April 2004, saying she had gained 25 pounds, experienced morning sickness and that her menstrual period had stopped.

Montgomery, 39, has pleaded not guilty to kidnapping resulting in death, and her attorneys are pursuing an insanity defense. They contend she suffered from several mental illnesses, including a condition that caused her to believe she was pregnant.

Prosecutors allege Montgomery was faking a pregnancy for months before she strangled Bobbie Jo Stinnett, 23, at Stinnett's home on Dec. 16, 2004, cut out the baby girl and then passed off the infant as her own. Stinnett was eight months pregnant.

McCandless testified that Montgomery told her that she had delivered a baby on Dec. 13, 2004, and "I may not have done anything and let the baby die."

Montgomery claimed to have buried the baby on her property in Melvern, Kan., and said she thought the body was still there, McCandless said.

McCandless, who had diagnosed Montgomery as suffering from bipolar disorder, depression and as psychotic, said Montgomery believed that a test she was given would prove that a tubal ligation she had undergone in 1990 had naturally reversed. But Dr. Gene Vandenboom, an obstetrician/gynecologist, said the test showed that the procedure was intact.

During cross-examination, prosecutors emphasized that the interview in which Montgomery mentioned the Dec. 13 birth occurred after her trial had started and that she had heard some of the prosecution's case.

Prosecutors also played tapes of two telephone calls between Montgomery and her husband, Kevin, in which Montgomery discussed "ways to mess with the psychologist" and is heard laughing while saying that she had told a psychiatrist that she heard voices.

Prosecutors said they will seek the death penalty if Montgomery is convicted.

Besides convicting or acquitting her, jurors could find Montgomery not guilty by reason of insanity. If that is the verdict, she would undergo a mental evaluation and a judge would decide if she will be released or committed to a mental institution.