Tonight I watched Nancy Grace's show on CNN to see if Jessica's Father would be on again. Some of his responses, again, seemed strange, especially during his answers he would move off topic onto something else. I noticed when he did this, Nancy would quickly interupt and hit him with another question. Also, Nancy always makes a point in each of her interviews to mention that he took a voice stress test and a polyagraph test. Sometimes she asks him if he took them or she just states that he did and passed both, driving home the point that the police probably aren't looking at him anymore. By doing this, I feel she is trying to make him feel at ease.
I think the authorities work with these news people and ask that they interview the family members as much as possible, hoping they will learn something from what they say or don't say. Since Grace is an ex-prosecutor, she knows how to ask questions of people that may be of interest to the police. This seems to be the case because Jessica's father practically has his own show each night, and her interviews with him come close to being police interviews without him knowing it.