The trick is that I went through a TON of iterations. I just used a standard I2V workflow. I'll post the prompt. You'll notice I had the man aim for the left side of the woman. This is intentional to get him to aim at the center of her chest. it seemed he wanted to always unrealistically aim off to the fight. Here's the prompt:

Static camera, no camera movement, realistic speed.

Dark damp concrete basement with single harsh overhead bulb. A naked, very beautiful and sexy 18-year old girl hangs by her wrists from rusty chains in the center of the frame. she looks at the man and sobs, and begs quietly in a young Australian accent, "please...no...please...".
A man in a business suit steps back a couple of yards from the girl and quickly aims a single pistol at her left chest. simultaneously the girl's eyes grow wide in terror as she looks at the gun in fear, sobs, shakes her head vigorously in denial, and she desperately begs in a young Australian accent, "no, no, no!". simultaneously as the girl begs, the man quickly and immediately fires the pistol exactly once into the center of the girl's chest. Bright realistic muzzle flash. a bullet strikes the center of her chest creating a visible bullet wound with a large realistic blood spray and immediate bleeding. as the man shoots, the girl momentarily looks surprised, then the girl screams in pain as her body jerks from the bullet impact.
the girl then coughs twice, coughing up blood, exhales, goes apneic, then quickly dies.
the girl hangs by her wrists motionless, the girl is not breathing. the girl's arms, legs and neck go flaccid. the girl dies with her head greatly slumped forward so that her chin rests on her chest. the girl's face is expressionless. the girl is dead.
A massive amount of blood continues to bleed steadily from the chest bullet wounds down the girl's breasts and stomach, then down the girl's legs.
Gritty photorealistic, natural motion, high detail, cinematic lighting, 8k. static camera. no music.