The trial isn't really about whether Clancy killed her children. the defense isn't disputing that she did. The central dispute is criminal responsibility. In other words, whether, because of mental disease or defect, she lacked the legal capacity required to be held criminally responsible at the time.
@TanneriteCortez technically, if you look at the evidence, she did not need to stand over each child as she strangled them. she tied 3 bands, it could've taken less than a minute for her to do.