Transcript for 'Honeymoon Killer': Prosecution's Strategy
We'll get to. Him pleading guilty in Australia in a moment but first. The bottom line for the prosecution understand that they've got to try and convince these jurors in essence -- -- doesn't make sense that what he saying happened. Couldn't have happened that way is the best argument that they -- That he's changed his story to other witnesses won't back up his account of what occurred. Because you know we talk about motive a lot in the context this case and you don't have to prove motive in -- case that's very important in the context to this case. And the motive here isn't that strong I mean you're talking about the idea that this guy. -- his wife bubble -- Dietz. For a 100000 plus dollars. But he's not even gonna get meaning because in the end the insurance policy wasn't even in his -- his -- that's riders so it. That's that's a pretty weak motive in my -- see you've got to have. Evidence that's pretty strong that says there's simply no way. That this could have happened in the way that he's laid it out and his story is clearly a -- what about these witnesses that they say they're gonna fly up from. Australia and they feel that their testimony will be very strong -- -- logistical. Difficulty that's going to be -- -- you're talking about flying people in to talk about an incident that occurred. Almost nine years ago at this point. And that's not something that the prosecutors ought to be relishing. But they're gonna do it. They're gonna make sure that the key witnesses the people who were there -- the people who spoke to him in the immediate aftermath of this. Come in and testify about what happened this -- -- sort of technical case you have to kind of understand. The ins and outs of scuba diving to understand. How much error. She could've used how deep he should've gone what his reaction should have been what an experienced rescue were -- -- would have done these are all crucial question. As prosecutors are also trying to say his behavior was very bizarre we heard what Elizabeth said in her report about the engagement ring and then -- and then also reportedly that he tried to. He did some things of his wife's grave site. That's right that there were items that were brought to the grave site and the authorities believe that he was literally removing them some of them even there were there with chains. -- he would take them from the grave site but. That's to me -- as significant and if they're going to get a conviction. In a case like this it's gotta be about what happened there it's gotta be what happened at the scene and the story that the prosecution presents. Has to make sense at all and I always say in cases that are like this motive isn't that important I do think motive is important here because you have to figure out. Why would he have been doing this in this way in the -- after his wedding if you like -- -- don't view. This. This insurance policy as a significant. And -- button here as -- says they're not gonna know that he pled guilty. To manslaughter in Australia and it doesn't matter that he went on trial there. Right he had no double jeopardy because it Australia US to totally different legal communities and as a result that he can plead guilty and served time there. And then be tried here as well we'll see what happens here -- all right Dan thank you.
This transcript has been automatically generated and may not be 100% accurate.