William spedding is at the centre of his case, do I really need to put up a link.
Here you go:
‘Forensic psychologist Dr Yule said police were working on a reasonably narrow abduction scenario.
"There may be a misconception that there is a lot that we don't know about this case. I've visited the crime scene multiple times and there is a lot of information that that location tells us," Dr Yule said.
"Combining that with assessing all the leads that have come into the investigation so far, there really are a limited number of possibilities that can account for William's disappearance and from that there are actually a lot of inferences we can draw about what has likely happened and the likely personality of a person or persons who may be involved."
William vanished from a dead-end street on the edge of a small town. No one but his parents and grandmother knew in advance of his visit to Kendall.
This has made police confident that the person who kidnapped him was already in the area.
"You would have to have some other reason to be there and take that opportunity; either visiting, residing or working in the vicinity."
There was only a narrow window of opportunity to take William, who was snatched in broad daylight and with a significant risk of being seen by someone on the balcony of William's home as well as neighbouring properties.
This has made police certain that the kidnapper was impulsive and took tremendous risks.
And if they took tremendous risks, mistakes were almost certainly made.
"It does seem that this was an opportunistic crime and when somebody makes that kind of impulsive decision, mistakes are made and it's those kind of mistakes that the investigation is focusing on," Dr Yule said.
No one has been arrested over William's disappearance and one person of interest has been publicly identified, washing machine repairman Bill Spedding.’
http://www.smh.com.au/nsw/inside-the-mind-of-william-tyrrells-abductor-20150911-gjkqyz.html