I'm so sorry for your loss.
It sounds like there are some questions of fact that need to be answered, such as how she was injured and what her boyfriend's role was in the incident. I would certainly encourage you to call your local law enforcement department. Your making a call as a grieving parent might be more impactful than a call from an ER nurse.
Certainly, if you're questioning the circumstances around your daughter's death, dont hesitate to call law enforcement or to contact a wrongful death attorney.