Martha mentions Ted Bundy in comparison to the Park Maniac. They both similarly received many love letters from female admirers while in jail. The Park Maniac actually married one of his admirers, who later filed for divorce due to his agressive behavior.
The main character (Helena) is fictional. The director did this as a "historical repair" for the women who were murdered by the serial killler.
Martha gives the typewriter that once belonged to their father to Helena. Mel Lisboa (Martha) starred as Annie Wilkes in a Brazilian stage adaptation of Stephen King's "Misery" in 2023.