Answer the following question: Extract the answer to the following question from the movie plot. If the question isn't answerable, please output "Can't answer". Question: How did Aileen kill her first John? Title: Monster Movie plot: After moving from Michigan to Florida, Aileen Wuornos, a prostitute, meets Selby Wall in a gay bar. After initial hostility and declaring that she is not gay, Aileen talks to Selby over beers. Selby takes to Aileen almost immediately, as she likes that she is very protective of her. Selby invites her to spend the night with her. They return to the house where Selby is staying (temporarily exiled by her parents following the accusation from another girl that Selby tried to kiss her). They later agree to meet at a roller skating rink, and they kiss for the first time. Aileen and Selby fall in love, but they have nowhere to go, so Selby goes back to her aunt's home. After being raped and brutalized by a client, Vincent Corey, Aileen kills him in self-defense and decides to quit prostitution. She confesses her action to Selby, while Selby has been angry with her for not supporting the two of them. Aileen tries to find legitimate work; but because of her lack of qualifications and criminal history, prospective employers reject her and are occasionally openly hostile. Desperate for money, she returns to prostitution. She robs and kills her johns, each killed in a more brutal way than the last, as she is convinced that they are all trying to rape her. She spares one man out of pity when he admits he has never had sex with a prostitute but eventually kills another man who, instead of exploiting her, offers help. Aileen uses the money she steals from her victims to indulge herself and Selby. However, as Selby reads in the papers about the string of murders, she begins to suspect that Aileen may have committed them. She confronts Aileen, who justifies her actions by claiming she was only protecting herself. Horrified, Selby returns to Ohio on a charter bus. Aileen is eventually arrested at a biker bar and speaks to Selby one last time while in jail. Selby reveals some incriminating information over the telephone and Aileen realizes that the police are listening in. To protect her lover, Aileen admits she committed the...
Answer:
Self defense