The problem is pointing fingers & filing lawsuits won't extract investors from the mess.  The company remains short of money - suing won't get shareholders compensation without a protracted fight - look at Nortel a decade later. Look at the Chinese companies that are emerging as frauds - the fight has just begun but estimates of any significant recovery are about zero after all the legal bills.  I've been burned a few times and the only recourse for a small shareholder is - take the loss ( for taxes) & join a class action suit - I'm almost 4 years into one class action with no end in sight.  Don't rely on the securities regulators as they are generally useless - been there on a couple of fights only to be told in one case where management was doing things that were to the disadvantage of small shareholders that it was a matter for corporate law to settle & I'd have to go to hire a lawyer & fight - took the loss & walked away as lawyer fees would be huge. 

Lessons learned & I've been an investor for over 30 years - do your own due diligence as best you can & don't rely on the analysts except to confirm what you've come to for a conclusion.  I've even climbed on a plane & flown as far as to Africa and South America to actually see/ interview & confirn the numbers with management of the company in operation before investing - even interviewed customers and suppliers in one case.  Even then you sometimes get it wrong.  My mistake on the Chinese company I lost big on is I relied on the so-called-experts & broke my own rule of doing my own due diligence otherwise I would have spotted warning signs. In retrospect I should have climbed on a plane.

Other lesson is have a stop-loss on all significant holdings.

On NAU - I was lucky having bought low a few months ago & as the price weakened after a nice climb it triggered my stop-loss  BUT I haven't written this company off - I sit, watch, & wait for the full story to emerge & may take a gamble if the price is cheap enough.  (Look at CMK where the sky fell ($2 fall to $0.045  but look at he huge recovery on it to $0.16)  There's sometimes a lot of money to be made if you have a strong stomach for high risk. Looking at the mess I do agree that some warnings should have triggered a long time ago - something isn't right.