likely say, the other guy did it. >> especially in a case like this. >> reporter: so he sent out his investigator, hoyt hoffman, to second guess the police. >> you have to make sure that no stone is left unturned. >> reporter: and then, they strategized -- >> we spent i would say half of -- or more of our time actually working it the other way, saying, "okay, well, let's say that the other person did it." >> nathan. >> nathan. let's say nathan did it. or let's say ashley did it, and -- and let's look at the evidence, and does that bear fruit or is that something where you look at -- at them, and it just -- it just doesn't work? because we wanted to make sure we got the right person. >> could you have prosecuted nathan? >> absolutely. absolutely. i mean, it would've been -- it would've been an easy case. >> really? >> -- to say -- absolutely. to come in and say, "he did it, he's the boyfriend," any time you have a stabbing, you immediately look to whoever that person is romantically involved