Angel of mercy (criminology)
An angel of mercy or angel of death is a type of criminal offender (often a type of serial killer) who is usually employed as a medical practitioner or a caregiver and intentionally harms or kills people under their care. The angel of mercy is often in a position of power and may decide the victim would be better off if they no longer suffered from whatever severe illness is plaguing them.
Source: Wikipedia — Angel of mercy (criminology) (CC BY-SA 4.0)