Theories

This Section Will Contain Spoilers!

This letter from Dr. Richter to Dr. Hawkins speaks volumes to how Richter viewed Lilian Grayson. He speaks lovingly of her repeatedly. He mentions that he had grown fond of her and that she was full of life. He calls her a bright star and that her loss is a "most unfortunate event". 

He speaks of her as a lover would speak and not as a doctor would speak of a patient. This most certainly would give credence to the theory that he was the father of her possible child and was having an unwilling, on her part, relationship with her.