Lynchings are no more "applied justice" than premeditated murder. Unfortunately, Dominican-brand justice will punish the unconfirmed perpetrators of this alleged robbery attempt and will probably celebrate the true criminals, as you have.
Unconfirmed perpetrators? Alleged robbery? I assume that you mean, by these, that no court of law established these facts beyond a reasonable doubt? To follow this reasoning to it's logical conclusion - these thugs should be walking the streets today, because likely the unwavering efforts of the local detectives, combined with the efficiency and ability of the judicial system to deliver justice in a timely fashion, would have quickly resolved the problem, given the opportunity? Puhlease.
It's pretty easy to take the moral high ground - until you become a victim. Has it occurred to you that you could have been the next robbery victim? And conceivably NOT walked away from it?
Laws and goverment are instituted in an effort to provide for public safety, first and foremost. When they fail at this fundamental task on an ongoing basis, what's the solution? While I don't advocate suspension of the legal system (partly because it has, to large degree, suspended itself!), at what point is it less than morally outrageous for citizens to rid themselves of these vermin, in whatever manner is available to them? It's not a big stretch of the imagination to think that other criminals, reading about this, hesitate more to rob tourists tonite, than they would if the story ended with "officers are investigating the robbery".