matthew durkan, a deputy colorado state attorney general came on board, he was later joined by ryan bradley, on loan from the boulder county da. >> what was your first impression? >> very tough case. >> they combed through the case file. fred statements, leslie's autopsy and all those tests conducted at the creek. >> this location was a breathtakingly beautiful case in the middle of nowhere. it was the perfect place to commit a murder where nobody would see. >> coming up -- >> authorities take a closer look at the scene. >> the defendants story did not match up. and for the mueller kids, a shock. >> i was just like, why? and i said all we can tell you that. >> a new chapter opens but nothing in this case will go the way anyone thinks. when dateline continues. people can get it bad. and for those who do get it bad, it may be because they have a high-risk factor. such as heart disease, diabetes, being overweight,