how suspense is created in "The Step Father"

suspense is created at the begining of the film as we see a normality established, as the character david does the usual norm by shaving and having coffee, and puts the radio on, so we can see every thing is casual, later this becomes subverted as he dies hes hair, this leaves a question to the audience thinking, why?
then we see the dead bodies.

Suspense is created in the scene were the cat jumps over the old lady, we would have assumed it was the killer, but we are relieved that its not the killer,  this is called a false plateau, soon after that the killer appears.

suspense is also created by a Bomb Theory when the man is in the supermarket again and meets a women, the audiences know that he is the killer, but the character doesn't.