ssion that began after the birth of her first child, Noah, in 1994. Her doctors documented periods when she heard voices, had visions and became so unhinged mentally that they diagnosed her as psychotic. But was she insane the morning of June 20 when she killed her children, one by one? Her lawyers say she is not guilty by reason of insanity. Prosecutors have charged her with murder and are seeking the death penalty. . A jury will decide whether Yates is mentally competent to stand trial -- that is, whether she understands the proceedings against her and is able to assist the lawyers preparing her defense. If the jury finds her incompetent, the trial will be postponed until she recovers. If the jury concludes Yates is competent, she will go to trial. The odds are against her. An insanity defense is extraordinarily difficult to prove. It is rarely used in court and even more rarely succeeds. In this case, prosecutors contend Yates not only was sane when she drowned her children but also is competent to stand trial. She has been treated by two psychiatrists and prescribed medication during her 3 months in jail. People who know her say she has improved. Insanity and competency are different legal terms that apply to different time frames -- the time a crime was committed vs. now. At the hearing, the defense lawyers plan to call at least two expert witnesses to testify about the extent of Yates' illness. The lawyers also have filed with the court more than 1,000 pages of medical records that portray Yates as so depressed -- ''nearly catatonic,'' the records say -- that one psychiatrist began court proceedings last April to have her involuntarily committed but stopped after she agreed to sign herself into an area hospital. On the morning of June 20, Yates drowned Luke, 2; Paul, 3; John, 5; Mary, 6 months, and Noah, 7 -- in that order -- after her husband, Russell, left for work. She telephoned police, called them to the house, and then gav...
