Lust is an emotion or feeling of intense desire in the body. The lust can take any form such as the lust for

The device used to kill the prostitute

knowledge, the lust for sex or the lust for power. It can take such mundane forms as the lust for food as distinct from the need for food. Lust is a powerful psychological force producing intense wanting for an object, or circumstance fulfilling the emotion.

In religion

Religions, especially Christianity, separate the definition of passion and lust by further categorizing lust as type of passion for something that does not belong to oneself, therefore being morally wrong. While passion for proper purposes is maintained as something God given and moral.

Method of killing

victim is knifed to death by her (sex trade) client wearing some sort of lethal strap-on device, while a gun is pointed at his head.