Ticking sound: There seemed to be this bomb-like ticking sound playing whenever something bad was going to happen. It came on at the beginning in the opening title sequence when the body's on the floor were revealed, after that it acted as a warning to us viewers to look away. This was accompanied by other tense, repetitive music to evoke suspense.
Dramatic Irony: Throughout the film we are aware the stepfather was a murderer, and as the family slowly warmed to David and believed his stories I became increasingly concerned for their safety as I knew what he was capable of. Also, there was constantly suspicious characters questioning Davids behaviour such as the aunt and oldest son. This increases suspense as the old women in the neighbourhood warned the family about him and she got murdered, so I became worried for the other concerned characters as I know what will happen if David finds out.
Change of Identity: Before the dead bodies are revealed to us at the end of the opening title sequence, David inherited a new look when he changed his hair, beard and eye colour. Also, at the end when David is approaching a new women, his look has changed once again, this came across as disturbing to me and built suspense as to whats going to happen to that new family.
Feeling of Normality: The setting of the film was in the suburbs showing the family is pretty much your average family. Also, David's real identity is stored in the basement which is why he spends most of his time down there, however this is unknown to the other characters which creates suspense as the dad spending time in the basement is considered a normal thing. This makes me feel paranoid and think it could be anyone stashing dead bodies in the basement when they say they're fixing things.