Just to bring up some things. I believe the BF is a independent contractor and most likely works out of the home with no employees. LE could have pinged his cell. I'm sure since they investigate the family first dogs where brought in and all vehicles were also checked. He also may have a alibi for that time period that LE knows about. He may come and go throughout the day depending on how close he is working. This could make it confusing to give an answer. I just think that as Marlene said, LE cleared him and she didn't want the show to become the way it did. I would be upset myself if it were me. I will leave it to LE to sleuth the family.
Another thing I find confusing is they keep showing photos of a sweatshirt that Sierra was wearing with the logo but then I heard LE say there was a t-shirt in the bag that was thrown. So was it a sweatshirt in the photo and a t-shirt in the bag or was it just worded differently. They have only said that the shirt that was found was similiar to the one in the photo. NG said that they beleive it was the one she was wearing in the photo. What NG said twisted the true statement up.