I'm not saying this is the case, but there is a possibility that this was done by a patients family member.
I am an RN and have been for over 20 years now. There have been incidents of physicians being killed out of grief or anger in the past.
Things have changed not only in our society, but in the medical field. I had a patient two weeks ago that got angry when the physician wouldn't order additional pain medication. His statement to me was, "You'd better hope I don't see you, or any of you racist bi*****s outside this hospital, cause I'll kill every last one of you bit***s." It's nice to go to work and bend over backward to try to help someone and end up being threatened. Sheesh.
That actually is a very good point. She worked in pediatrics. Police need to look into the parents of patients and see if she lost any patients recently (or any patients had complications, etc).