Yup. Dr. Penelope Young was one of the psychiotrists that appeared in Batman Arkham Asylum. She is also the one who helped create the titan formula which turns anyone injected with the serum into monsters. Originally she had it planned to help cure the patients of their insanity but when Joker brought it up to her during her interview with him, she realized that she was being tricked into creating a serum that would give him a super powerful army of monsters that would help him destroy Gotham and so she backed out of the deal which leads Joker into escaping Arkham and planning his take over on the asylum. Surely because of how Joker likes killing people so much it's obvious that he wanted her to know. Clearly Penelope doesn't get why Joker wouldn't listen until Batman saved her from Zsasz and explains to her that "Joker doesn't take no for an answer!" When Young tries to get the codes from the Warden's safe, she noticed that Joker got to it first as she saw a green smile smeared onto the terminal that she knew right away that it was a bomb and ends up getting killed in the explosion at close range. Despite what she had done wrong, her death was the most dramatic and saddest one of all in Batman Arkham Asylum.
But before her death and just as Batman got into her office before scanning for her fingerprints, her computer had shown a wallpaper of her with someone else during the day of her graduation
This man shown in this picture with Dr. Young on her computer could her father, her brother, her boyfriend or just a dear friend of hers and if I am right, this man that Penelope was with could in fact be the Arkham Knight. After all the manager of the studios having the Arkham games developed says that the Arkham Knight is completely original, meaning that just like Dr Young and if the Arkham Knight is this man in the blue shirt that Young was with during her graduation, then her death could be the very reason why the Arkham Knight wants to kill Batman, because of the fact that he loved Doctor Young so much and because Batman wouldn't kill Joker for not giving up his murderous threats upon Gotham City that he just kept letting more people get killed over his intentions on wanting to make a difference, then it's obvious that the Arkham Knight teamed up with Scarecrow and the other villains of Gotham on terrorizing the city together just to make Batman regret doing what he does.
To find out for sure if this theory is true, stay tuned for more updates on Batman: Arkham Knight.