Taking Lives

The film begins with a young man (Paul Dano) who has run away from home. He looks meek and soft, a geek with thick glasses. He shares the bus trip with another male runaway who has jumped free from an army school called Matt Soulby (Justin Chatwin). The bus gets a flat tyre, so they buy a second-hand car from a garage man (Bill Two Rivers). That car gets a flat tyre as well. When Matt is changing the tyre, his companion pushes him onto an incoming car. Both Matt and the driver of the car die.Angelina Jolie plays an FBI profiler, Special Agent Illeana Scott (Angelina Jolie), who is sent to Montreal to help in a murder investigation. Agent Scott's approach to profiling the serial killer is somewhat eccentric. She goes to a crime scene, lies down in the position the victim was found, and uncovers clues the police did not notice. She gets inside the head of the serial killer and comes up with a theory that the killer is assuming the lives and the identities of the people he kills.The mother of the serial killer, Mrs Archer (Gena Rowlands), sees her evil son, who was supposed to have been killed by a truck years earlier, on the ferry. She goes to the police and talks to Paquette (Olivier Martínez), but they do not let him reopen the case. Later, when the serial killer kills again, they have a witness who is an artist called James Costa (Ethan Hawke), who can draw his face. This was the clue they needed although Costa can't be too specific about the details. The police finally contact his mother and collect more information about him. The murderer was the non-preferred younger sibling of a pair of twins. Illeana insists. The police are protecting Mrs Asher, but she doesn't allow them to register her home. Illeana enters the home, thinking that she'll get off easier of the charges as she is an outsider who may not know the rules which are applied in Canada. There, she goes up to the penthouse and looks to a shabby place full of old-fashioned toys, a teddy-bear which has been hanged... Suddenly, she is attacked by somebody who appears from under the dirty mattress and runs away.Agent Scott gets involved romantically with Costa, clouding her judgment, so she wants off the case. However, the Canadian police think that she is their best assest, so they keep her on the case. They think that the killer may be one big potential buyer of Costa, so he'll be used as bait. Costa goes to the toilets after having received a note, but the police tell him to forget about everything - although there is a suspense moment when the police cannot hear Costa and he goes to the bathroom on his own.The investigation goes on, and Costa finally confronts his evil twin: Hart (Kiefer Sutherland). In the ensuing fight, Costa is hurt, but Hart jumps from the window and leaves in his flashy car. The police run after them, and Hart's car burns to ashes to Hart inside. Costa is hurt but alive. That night, he and Illeana make love.Mrs Asher has to identify her dead son. She gets shocked and leaves without saying anything after looking into the corpse's eyes. The police laugh at her. Illeana goes after her because she smells something fishy.Mrs Asher has already gone into the lift. Costa is inside: he is the evil twin. His mother says that she's not afraid of him. When Illeana arrives, Mrs Asher has been killed and lies in a pool of blood.Costa has left to the underground. He starts talking to a man, and he takes his life, as usual. Leclair (Tchéky Karyo), the man in charge, is angry with Illeana because Costa has run away.Time goes on. Illeana goes back to the USA and she is spelled from the FBI. She has become white trash, living on a derelict wooden house somewhere in the countryside. She is pregnant.One day, Costa arrives with a physical appearance somehow different. She wants to kill her because she is pregnant of his babies, male twins. There is a fight: he has taken away all the loaded guns Illeana had hidden away all over her home.James takes a pair of scissors and he thrusts them into Illeana's womb. She takes the scissors and thrusts them into James Costa's heart. While he is giving his last breath, Illeana shows him how she has tricked him. She is not pregnant at all: she has carried a fake pregnancy bag on her belly under her clothes. James Costa dies.Illeana phones Leclair. He says that he's glad to hear from her, as he was beginning to feel worried about her. Leclair will go immediately to Illeana's home to save her some of the trouble with the questioning and paperwork.

Question: Who do the Canadian police use as bait?
Answer: Costa