I guess one of two things will happen tomorrow:
-The Daily Mail will issue a mea culpa (or just edit after the fact) to reflect that the guy in the still shot is the same guy that the police have eliminated as unrelated and not a POI.
OR
-LE will reveal that they are investigating the DM's lead.

my money is on option 1
My feelings about the Daily Mail are mixed: Yes, they often seem to pull together the full story with lots and lots of pics, sometimes a useful map and, bless them, a timeline...which we just love! I just think that sometimes they are a little too hasty to rush to publish at the expense of fact-checking and they often later edit their 'facts' within a story without reflecting the retraction or mistake from the original text.
With that said, I think the Daily Mail does not have the same resources and legal clout as the LE offices of a few states plus help from the FBI and so I am really not sure why they are choosing to print the image of this guy as if it is a 'scoop' and as if the police have not already seen and discounted this image for whatever reasons they have.
-Right now, the only way I can believe that another party was involved in Rita's road trip is if this information comes from police at a press conference or if new traffic cam or third party footage is found. The police have surely followed through on the places it has been confirmed she has visited.
As an aside, and thinking back to a previous case...A passing thought of an assisted suicide entered my head this weekend as I know there are organizations (and probably some less scrupulous "guns-for-hire) out there that, for a fee, can help with exiting the world (and concealing the fact of suicide). I think the possibility of Rita enlisting the help of someone for this purpose and the day playing out the way it did is extremely unlikely...