Visible crew/equipment: When Mr. Hammond drives up to the school where his daughter died, you can see the reflection of the microphone in the left side of Mr. Hammond's car.
Visible crew/equipment: When Kim is in the empty gym dancing, Wendy shows up to confront her. When the camera is on Kim you can see the boom mic coming from the bottom of the screen.
Visible crew/equipment: Kelly gets spooked and heads to the door to check to see if anyone is around. She proceeds to open the front door and the scene quickly cuts to an exterior shot of her looking out the door, and right above the door is a black boom microphone.
Answer: Alex is not the typical one dimensional slasher serial killer, but rather a complex individual with conflicting motivations. The lipstick is a symbol that he is portraying the hurtful people from his past even as he kills them.