During the investigation, Olga Hepnarová confirmed her intention was to kill as many people as possible and she expressed no regret. Psychology experts found her fully aware of her actions. She planned her actions, as she considered a slope leading to the stop. That allowed her to gain speed for the maximum death toll. The collision was her second attempt, as she felt there were not enough people on her first run.
One psychiatrist, one of the few people Olga Hepnarová actually opened up to, eventually diagnosed her with schizophrenia. Two years later, in 1967, a week before her 16th birthday, she wrote him a letter, updating him about her state of mind. She told him that she hadn't spoken to her father since her last beating, and that she now had nothing to talk about with her mother. She then expressed her view on society in general, writing: "I hate people. I wonder how my relationship will look as time goes by. I want the people to not exist for me at all, their words and chatter are indifferent to me. That's what I want. It's better for me when I'm alone than when I'm with them...Everyone falls for their smiles and fellowship. They mutilated my soul."