Vigilante Justice
Hayley is a vigilante. It is not something that she has set out to become, but something she has become out of a necessity, having learned that many men who are guilty of the most horrible of sex crimes simply get away with it, all the while going about their daily life behind a veneer of decency that others seldom see through. If the justice system had stopped men like Jeff Kohlver from committing rape and murder than people like Hayley would not be needed; however, she sees herself as the last resort, and the only hope in the battle to keep women safe from predators like this.
Although at first Hayley's form of justice seems incredibly violent, she perpetrates very little actual violence; most is actually a form of self defense. The justice she dispenses is predominantly in the form of mental torture. For example, she numbs Jeff's genitals with so much ice that he cannot feel anything at all and does not know if she has castrated him or not until she leaves the room and he looks himself. She also threatens him with a gun but does not use it. Hayley's intent is to drive Jeff out of his mind and compel him to commit suicide, rather than to commit a revenge murder herself. In this context, vigilante justice is not a violent thing but a mental and psychological one.
Sex Crimes
Jeff is a pedophile, a rapist and a murderer who kidnaps young women with the express intent of raping them and killing them afterwards. He is generally in partnership with a friend, Aaron, when he commits these crimes. Jeff feels no remorse and is a predator. The sex crimes theme actually shows the audience how a man like Jeff would go about finding a victim, seducing them and then raping them; his relationship with Hayley, though new, has been entirely online, and sexually charged from the start. He then suggests an in person meeting at a coffee shop - designed to put his victim at ease. After all, who would feel at all threatened meeting a man, even a stranger, somewhere so public as a Starbucks? We then see how his skilled manipulation gets him what he wants; he is flirty sweet, self-effacing, and completely fake, showing young women exactly what they need to see in order to trust him.
Jeff is known to have raped and killed Donna Mauer, although denies this, but keeps a photograph of her in his collection of violent pornography. Like many killers, he keeps trophies of each murder, although again, he denies this.
The Murderer Next Door
Jeff's neighbor allows her daughter to sell Girl Scout Cookies at Jeff's door. Clearly this would not be the case if he seemed at all strange or threatening. One of the film's themes is the fact that anyone can live next door to a murderer and have absolutely no idea about it. Jeff seems completely normal. He has an exciting job as a photographer. He keeps normal hours, keeps a nice home, is a good neighbor. He seems to have a good relationship with a beautiful girlfriend. He is a normal, decent man - on the outside. This shows that the face people show to the acquaintances around them is often a facade that hides something far more heinous underneath.
