Doesn’t it seem a bit off that in the five weeks he had to think about what he was going to say the best he could come up with is leading them to a body?
The problem is that he doesn't know the training and skill from the people interviewing him.
Those LE people (local ,state and federal) are EXPERTS in discovering deception. If the story is made up, there is almost no way, when questioned to the Nth degree, that these investigators were not going to find the (not thought out) holes in his story.
Once they got him to acknowledge that he was driving the car where the license plate was read shortly before she was abducted... then the trap was set.
Did you see her? ("no - don't remember seeing anyone jogging").
Why did you drive back around twice? ("I was just driving around and around")
You had to have seen her.. she was only 30 seconds ahead of you and we caught you with your brake lights on (this is a lie... just to get him to adjust the story). - ("Well, maybe I did slow down so I didn't hit her."
But you just said that you didn't see her? "Well.. maybe I did. I must have but I don't remember."
So, if you did slow down, did you stop? "No I didn't stop".
You are lying to us.. we have you on camera stopping your car! (This is also a lie) We will ask you again, did you stop and why??? "Well, yes I did. She was running out in the road so I stopped to tell her to get off the road because it is dangerous"
So, you ALSO talked to her? "Yes, I told her to get off the road and then I got back in the car and drove off".
So, you got out of your car TOO??? "Yes, but only for a second to yell at her"
Did she talk back? "yes ,she said she would call the police.. so I left"
Etc, etc. to the final confession and location of her lifeless body.
You see, this is how these trained experts get to the truth. There is very little the guy could do if he was trying to conceal the truth.
I would like to think of myself as a smart person. I can give all the details logically of a real story when asked any question when I know the truth...no matter how off the wall the questions are. Therefore, if I am told a lie by the investigators, if I know the truth differs...then I know what they said is a lie...because I know the truth.
But if the lie they tell matches the truth, then I have to assume they know the truth on that point... so I am screwed on that minor point so I need to adjust my story to account for that minor deviation...but the slippery slope is set and investigators will employ a few lies here and there to get the perpetrator to change the story to where it is close to the real truth.
The best someone can do being interrogated like this is to not change their story to acknowledge a lie. But investigators also know some truth and know if the person is actually lying. Bottom line: Investigators have an extremely good chance to get a deceptively guilty person to eventually admit most of the story of what they have done.