A recent college graduate, who prosecutors said was high on pot, is accused of hitting and killing a man while changing a tire in the center median on a Vista freeway. 22-year-old Isabella Herrera pleaded not guilty Tuesday of gross vehicular manslaughter while intoxicated and driving under the influence of Drugs. MORE: https://www.cbs8.com/article/news/local/college-graduate-arraigned-for-hitting-and-killing-man-on-vista-freeway/509-bf5e15b0-6dd2-4b1a-a0a1-ad07d6b92453