Nicholas T. Moore (No. 110) - S5-E20
Continuity mistake: When they are in the hospital, Elizabeth is talking to the young girl and she closes the door behind her. The next time the camera shows Elizabeth's face the room door is open behind her. (00:06:15)
Answer: The man Red killed, Sam Scott, was Lizzie's adoptive father, not her biological one. However, at that time Lizzie (and thus the audience), was led to believe her real father abandoned her and her mother, so expect more secrets to be revealed how her real father actually died (or if he's even actually dead).
Bishop73