`` is used here in sense 4 from EDICT:
> 4. quite; reasonably; fairly; tolerably
>
`` could be roughly translated as "things like". On the more analytic level, it is a combination of the quoting `` and ``. I.e., here the author is quoting the things they've heard:
> I've heard plenty of stories like "they found the culprit" or "The child just disappeared like that", but is [any of them] true?
`` could have been used if it was describing the actual sequence of events, but since here it's hearsay it doesn't really work. Also, it seems that "they found the culprit" and "The child just disappeared like that" are two conflicting storylines and not sequential events, so `` doesn't work here.