Arnold was found dead in the Exhibition's Inventors' Hall, and when first informed about her father's death, Susie was dismayed and claimed that her father's beliefs about the Exhibition and inventions were true. Later on, a box of chocolates was found at the Exhibition, with hairs on it belonging to Susie. When questioned, the still grief-stricken Susie revealed that she had been meeting a gentleman at the Exhibition that morning and that she left in such a hurry that she forgot the chocolates he gifted her.
Ultimately, the player and Maddie O'Malley discovered that not only was Susie's lover inventor and Concordian Flying Squad member Charles Dupont, but she was also the one responsible for her father's death. When confronted with the evidence, Susie initially feigned innocence before snapping at Maddie's claim that she stole the electric gun used to kill Arnold, revealing that she'd made it herself. After that, Susie fully confessed to killing her father, revealing how she had been learning to become an inventor behind her father's back and how they'd gotten into an argument when he caught her leaving the Inventors' Hall following her rendezvous with Charles. During the fight, Susie attacked Arnold with the electric gun, killing him. Horrified by her actions, Susie fled the scene and later wrote a telegram to the police anonymously confessing to the murder, doing so out of remorse for killing her father (though she ultimately never sent the message).
During her confession, Susie tearfully expressed the guilt she felt over her actions, while also revealing that Arnold wasn't behind the recent string of invention vandalisms and that she'd decided against turning herself into the police after realizing that Charles would become a suspect. Susie was arrested and put on trial, where judge Satoshi Takakura sentenced her to seven years in prison. Following her sentencing, Susie broke down in tears as she proclaimed that she would never recover from the guilt of killing her father.
- "I see it's too late to deny it now. Yes, it's true. I killed my father. But he was just like you! He didn't think I could be an inventor! And he wouldn't allow me to study, though I love tinkering with machines! (Maddie: "How did you manage to learn so much if your father was so against progress that he went around sabotaging inventions?") What? My father wasn't the saboteur! He couldn't tamper with machinery if he wanted to. He didn't know the first thing about mechanics! But I learned a lot listening to all the inventors in this cafe, and my father was none the wiser! Until today, when he saw me leaving the Exhibition Hall! We had an argument, and... ... next thing I remember, he was lying on the floor, dead! And my electric gun was in my hand, still warm and buzzing! I wanted to go to the police straight away! I only changed my mind because I didn't want my rendezvous with Charlie to cast suspicion on him!" (Susie's confession to murdering her father, Arnold Nottingham)