Its called Munchausen By Proxy. Its a psychiatric condition where a person has a morbid fascination with Medicine and Health Care in general, tends to lionize doctors and nurses, and is attention-seeking. The person wants to be a "hero" and will injure or harm a patient or relative and then take steps to save them just in time or notify staff.
Other times they outright kill a patient by believing their were "ending their suffering".
They should be simply called serial killers and should be dealt with in the same way as other serial killers. They cannot be reformed because it is a severe mental health condition.