Lanthimos tries to be Kubrick in his cinematography and Bunuel in his storytelling Martin threatens Dr. Murphy's family in no uncertain terms. He even explains his motive. Murphy doesn't go to the authorities. Later, when he informs his wife about this threat, his wife replies "We're not going to the police. We're not tell anyone about this. What's the point?" This is one of many illogical and convenient elements to the screenplay that enables the poorly conceived story to continue.
Martin proclaims he and his mother live in a rough part of town, in a "not-so-nice" house. We then see Martin's big Victorian home in Hyde Park. They have ample food, nice furniture and clean clothes. I don't think the director/writer understands what low income Ohio looks like. It is ridiculous and reeks of classism.
Many shots are Stanley Kubrick imitations. The filmmaker, Yorgos Lanthimos, tries to be Kubrick in his cinematography and Bunuel in his storytelling. It's embarrassing. This imposter's style only fools pseudo-intellectual "wannabe" cinephiles.
How Martin has access to this karmic ability goes unaddressed. Neither are the repercussions (moral and legal) of murder. It's quite easy, and lazy, to write a story like The Killing of a Scared Deer because it doesn't have to follow the rules of logic. The film doesn't take place in a developed reality. It is a simpleton's fantasy without the responsibility of world-building.
The final (hilarious) icing on this cake of pretension is the claim that this film is a modern retelling of Iphigenia in Aulis. That is just marketing nonsense. Iphigenia in Aulis tells a proper story, with logic. The Killing of a Sacred Deer is a grasp for artistic attention from yet another perverted, mentally ill filmmaker.