The parents of a 7-month-old girl who was found dead in the heat of a parked car last month are not criminally negligent, a city prosecutor said Tuesday, although they demonstrated "questionable parenting and communication skills" that day.

Circuit Attorney Jennifer Joyce said she did not have enough evidence to prove criminal negligence beyond a reasonable doubt, "and that is the legal threshold for charging this crime."

Sophia Knutsen of suburban St. Louis died Aug. 23 when she was left in her parents' car in a parking lot at the Washington University School of Medicine.

Her father, Russell Knutsen, and her mother, Dr. Beth Ann Kozel, told police they miscommunicated about who was taking the child to day care.

The child was left with Knutsen, but he didn't see her because she was in the back seat in a rear-facing child seat.