My Mother Was Hit By A Car

My mother was hit by a car on the 27th of December coming out of work by a coworker who sped from the parking lot. My mother worked at a hospital. After the initial hit her coworker stopped immidiatelty and got help. My mother died on the 2 of January. She struggled for 5 days. We just got a autopsy back and it was due to bluntforce Trauma and a infection she had in the body. The nurse who hit her hasn't gotten charged, nor has she faced any repercussions. DA and the detective called today stating the she would face no legal actions. Since her autopsy included she had a infection in her body. The infection along with the blunt force trauma killed my mother. However the DA stated due to the infection they couldn't go after the nurse.

Please I'm desperate for help what can I do. This woman killed my mother and they won't bat a eye that she sped in the parking lot. That she took full blame. Is there anyway to rectify this. None of this is fair.