Some posters on this site seem to believe that there must be some very significant evidence against DR, otherwise they would not have investigated him so thoroughly. It has been suggested that this "evidence" might include proof that no "mystery" vehicle went up that driveway that day; greatly limiting who might have committed the crime.
There is an old dependable police trick. You approach a POI with information to the effect that you know he did it. You you imply, suggest or outright lie that you have evidence you do not (perfectly legal) and plead with the POI that the "gig is up", "your going down", make it easy on yourself" etc. This approach works best when the POI has never been "in the system" before. Many confessions are obtained this way (although a few "false confessions" are also obtained). Even if the POI does not confess, he might feel it necessary to change details of his original version of events, furnish verifiable untruths or otherwise say something or behave in a manner that might advance the investigation.
An extreme version of this includes disclosing information to the media that will encourage public perception that the POI is guilty. The obvious problem with this approach is that there is really no way to "clear" the POI if he stands by his story and does not confess.
The issue of what evidence and information to disclose is pretty dicey. Law Enforcement always wants any perp to believe they have more that they really do but releasing information and evidence can also encourage people to come forward with additional information. Releasing information that points in a particular direction might discourage information that might point in a different direction. Generally, they will be very up front with the sort of information/evidence that is rock solid but much more careful if they were not so certain.
I would expect that compelling evidence that no vehicle was used in the abduction would be well worth publicizing since is would focus all suspicion on DR (and perhaps a few other close neighbors) and anyone with "significant" information would be likely to come forward. This would also have the effect of pretty well "clearing" anyone who would have needed a vehicle. It would tend to discourage any forthcoming information on any of them.
From what I can tell, there were some media reports that once Kevin came forward, Law Enforcement was operating on the assumption that no vehicle was used and DR was the prime Suspect. Was this really "true" or was it all part of the "full court press" on DR. Since then, news reports don't seem to dwell on DR and are not so focused on the "no car" theory.
