Complex sentence: Sam abandons Dr. Harper, saying that she will claim innocence in the matter, so Dr. Harper locks himself in his office and tells Sam that he has the syringe with Sam's fingerprints on it, and awaits his inevitable arrest, expressing repentance for his actions.
Split into simpler sentences: Sam abandons Dr. Harper, saying that she will claim innocence in the matter. So Dr. Harper locks himself in his office and tells Sam that he has the syringe with Sam's fingerprints on it, and awaits his inevitable arrest, expressing repentance for his actions.