Read something I wanted to add to the thread - it sounds very much like the post-crime behavior of Steven Powell.
This is Sexual Homicide, Patterns and Motives by Robert K Ressler:
p.62
"The murderer's reactions after his initial response to his crime are generally tempered by the need for self-protection. He may dispose of evidence; he may keep a low profile; he may fabricate an alibi. However, his behaviors during this period often run counter to the need to avoid attention. (My note: Such as SP intending to post Susan's journals, etc.) These behaviors fall into one of four categories: 1) returning to the crime scene, 2) observing the discovery of the victim's body, 3) keeping souvenirs of the murder, and 4) participating in the investigation. Such responses illustrate that the need to sustain the excitement of murder often is so strong that it prevails over self-protective instincts.
p.63
"The murderer may even confess to the crime in order to accompany police to the location of the victim's body."
"Many murderers' postcrime behavior involves the keeping of various items, generally associated with the victim, as "souvenirs" (My note: such as Susan's LDS undergarment, her photos, journals, etc.) of the murder... The value to the killer of these items as reminders of the murder outweighs the risk of being identified through the possession of such incriminating evidence. The souvenirs provide the killer with tangible proof that he was able to activate his fantasy, as well as with a catalyst for further fantasizing.
...
"Often the items retained by the murderer are those for which he has a particular fetish."
...
"fetish items in particular provide sexual stimulation."
p.64
"The murderer's postcrime behavior may involve some form of participation in the police investigation of the murder.
..
"The murderer who injects himself into the police investigation indicates his need to demonstrate his power and control as well as to maintain an active involvement in the murder, the source of his excitement. He believes he can fool investigators, and he may write or call police, or even leave clues for them to find. He taunts investigators to catch him. He is actively engaged in trying to show his superiority; thus, he may have made the body easy to find. As one murderer commented, 'You wouldn't get the credit if it wasn't.'"
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Ok, so you may be wondering what relevance this has to this case. My thought on this is to use this information to lure Steve Powell into a confession. As a suggestion, I would have Steve sit in a room with one other detective, and bring out the fetish items he has of Susan and ask him to examine them, etc. I would get him to talk about these (very easy.) I would try to get him lost in his fantasy, and then see how far that can be taken with regard to getting Steven to talk. Other techniques to elicit a confession can also be used, such as plea bargain, etc. Who knows, a helicopter flight to the grave site might work. The best time to do this of course is after an accounting of what evidence was found from the search of his home.
MOO.