Well, what convinced me of their innocence was the DNA testing. Here's the section of the court order which helped them secure another trial later this year:
"The results of the testing established that neither Echols, Baldwin, nor Misskelley was
the source of any of the biological material tested, which included a foreign allele from a
penile swab of victim Steven Branch; a hair from the ligature used to bind victim Michael
Moore; and a hair recovered from a tree stump, near where the bodies were recovered. In
addition, the DNA material from the hair found in the ligature used to bind Moore was found
to be consistent with Terry Hobbs, Branch’s stepfather. The hair found on the tree stump
was consistent with the DNA of David Jacoby, a friend of Terry Hobbs."
Mind you, this is the same evidence the previous court would not allow into court because they felt it didn't prove the WM3 weren't at the site. But on the same token, in no way does it prove that they were. At the most, the evidence proves that Branch's stepfather was present, as was the stepfather's friend, when the boys were killed. That's now fact.
In order to think the WM3 was guilty, it would have to be believed that they did the killing, with the stepfather and his friend present, yet committed the murders without leaving a single, solitary trace of evidence that they were there. Which is impossible, unless the WM3 managed to somehow magically hover above the ground so as not to leave footprints, were wrapped in a coccoon which secured any hair, body fluid or skin flake from falling off their persons, telekinetically manipulated the tools used to kill them so as not to leave fingerprints, and forced Branch's stepfather's saliva onto Branch's penis, while also forcing the stepfather's friend's hair to fall out, there, on the scene.
Long story short, the DNA evidence now being allowed, if it doesn't clear them completely, at the very least presents a reasonable doubt. And so long as a reasonable doubt exists, a jury cannot, by law, deliver a verdict of guilty.
Even though they did the first time.
EDIT: Whoops. The allele found on Branch's penis wasn't the stepfather's saliva. Sorry -- this time, it was classified as an unidentified "foreign" allela. Branch's stepfather's hair was also found at the murder site, however.