Depends on which theory or report we accept as truth at the moment, but it also sounds like there could be negligence involved - and that can be prosecuted.

I'm sure there are some AG's and Prosecutors frothing at the mouth right now to get there hands on Mr. Karpeles.

Edit: Even if the judicial system doesn't get MK... his life is probably ruined at this point if he cannot recover the funds - either because of reputation or personal safety. Bitcoin is the Wild West and there seem to quite a few shady and nefarious actors within the community.

losing the money was not the crime, trying to cover it up and engage in dubious practices like using customer fiat funds to shore up your company, buy btc (on gox at $150) to sell on other exchanges (bitstamp at $500) is likely to be the root of their legal woes not that they wer ehacked and lost 750k coins.

Their cover up is what will bring legal repercussions.

I have no idea how accurate this is, but Mark seemed to believe they were "operating within the law":

"Karpeles replied that the matter is “confidential,” adding that the company had discussed its business model with Japanese authorities “to ensure that we are operating within the law here.”"

That sounds plausible. If they did cover it up, then I can see fraud charges. But if they were just stupid...

You can't for incompetence, but you sure as hell can for fraud.

Incompetence that borders on negligence can certainly be prosecuted.

Negligence that leads to bodily harm, ya; but negligence that leads to monetary losses is probably a civil rather than criminal matter. It depends on the jurisdiction for sure, some developing world countries might see it as criminal.