crime scene matched marks on a bullet found in smoot's home. his missing hand gun appeared to be the murder weapon. hat's a huge connection? >> it is pretty much the connection. >> reporter: in june of 2012, eight months after brooke was killed, shawn smoot was indicted on charges of first degree murder. did you immediately identify with her just being this young woman who was clearly so vulnerable? >> oh, absolutely. >> reporter: prosecutors bob edwards and tiffany starr smith saw this case as a relationship turned deadly. >> we're still talking about -- domestic violence. we're still talking about orders of protection, and all of the things that go wrong in those situations. >> reporter: you had no witnesses. you had no dna from your suspect. you had no murder weapon. that's a lot of things you didn't have. >> if we didn't feel like we could prosecute it, and be successful, we would've never indicted it. we would have never proceeded with it. >> circumstantial cases are --