Stephanie Rochester, the Superior woman accused of smothering her 6-month-old son, will not go to trial on first-degree murder and child abuse charges.Boulder County District Attorney Stan Garnett announced Monday that he does not feel prosecutors would be able to prove beyond a reasonable doubt that she was sane at the time of the 2010 killing.According to her arrest warrant, Stephanie Rochester told a police detective that she thought her son "was showing signs of autism" and she attempted to suffocate Rylan Rochester with a plastic bag before putting blankets over his head the night before he died."She wanted to kill herself, but did not want to burden her husband with the baby inflicted with autism," the affidavit stated. Her husband also told police that she had been depressed for some time and was taking the antidepressant Zoloft.Rochester worked for two years as a counselor at Children's Hospital and worked with children with autism, the affidavit said.Rochester has pleaded not guilty by reason of insanity. A defense psychiatrist and a court-appointed psychiatrist both determined that Rochester was legally insane at the time.A judge denied a prosecution request to allow their own medical expert to examine Rochester. Prosecutors last month asked the Colorado Supreme Court to consider allowing their medical expert to examine Rochester. The court declined to hear the case, blocking prosecutors' expert from assessing the woman."Given the Court's ruling and the state of the evidence at this time, I have determined that there is not sufficient admissible evidence for the prosecution to meet its burden of convincing a jury of 12 to reach a unanimous decision, beyond a reasonable doubt, that Stephanie Rochester was legally sane when she allegedly killed her infant son," Garnett said in a press release. "Based on that, I have determined that it is inappropriate to proceed to a jury trial in this case."Instead, prosecutors and defense attorneys will request a hearing in front of a judge to present the evidence of Rochester's insanity and determine whether she should be committed to the state mental hospital, Garnett said.This is the second high-profile case in recent months where prosecutors said they were hampered by a restriction on having their own psychiatric expert examine a defendant claiming an insanity defense.In October, a Jefferson County jury found Bruco Strong Eagle Eastwood not guilty by reason of insanity in the 2010 shooting of two eighth graders outside Deer Creek Middle School.Instead, Eastwood will be held at a state mental hospital until state psychiatrists decide he's sane and can be released.Jefferson County prosecutors have said they will pursue legislation in the coming state legislative session, because while three defense doctors interviewed Eastwood the judge ruled that the prosecution's psychiatrist couldn't interview the defendant under state law. Prosecutors say the current law denies district attorneys a "level playing field" during insanity evaluations.