How is suspense created in the film you watched in class?

My class watched the film "WHAT LIES BENEATH" which is a film full of suspenseful moments.
For example;

The part where Norman (the man in the film) appears at the back of the car that the woman (Clair) was driving when she was escaping from her house where Norman was lying dead on the floor, well she thought he was dead anyway but we as the audience, saw that he was still alive because he opened his eye as she ran out the door. This moment was suspenseful because we knew that he was alive but Clair didn't and we saw his shadow getting up off the floor as she drove off so it made us wonder wether he made it to the car or not because she drove of quite fast. Also, it was a suspenseful moment because as the camera was on her driving the car, we saw a shoe fall off so that made us as the audience wonder wether that was him or not. But as she stops the car to call police, he suddenly with shock appears behind her. This is called a false plateau.

Another example is;
The part where Clair is walking down the stairs backwards slowly, the music played made the scene suspenseful because it was the type of sound that gets you to feel that there is danger if she goes any further then she stepped on blood. The sound played when she stepped on blood was horrorfying because it made us think it was Norman's hand grabbing her or something but it was just blood. That was when she saw him lying dead on the floor.