MF Global's collapse late last October had all the makings of a classic Hollywood film. First was the magnitude: It was the eighth-largest bankruptcy by assets in U.S history. Then, the characters: farmers and small-business owners struggling to make ends meet. The McGuffin: $1.6 billion in missing customer funds. The protagonist: James Koutoulas, president of the Commodity Customer Coalition, who, in another life, would have been played by Jimmy Stewart, heading a coalition of customers determined to be made whole.

And, of course, there was an apparently cut-and-dried cast of villains, from lower-level executives to multinational banks. Leading the pack were Jon Corzine, former governor of New Jersey turned Goldman Sachs (NYSE: GS) executive turned MF Global CEO; JPMorgan Chase (NYSE: JPM), which was entangled in ways not immediately clear; and U.S. Attorney General Eric Holder, whose firm used to represent MF Global.

And we all watched, waiting for what we thought would be the inevitable ending: criminal prosecution, restitution, a triumphant celebration. But the plot hasn't quite unfolded along expected lines. This week, after a 10-month investigation, officials announced criminal charges against MF Global executives were "unlikely."

"If you can't be a good example...
 During an online chat The Motley Fool held shortly after publishing our series on The Astonishing Collapse of MF Global, we polled participants on whether they thought criminal charges would be pressed, and if so, against whom: 71% thought someone would be held accountable and sent to prison. Most thought it would be Corzine. Others eyed JPMorgan CEO Jamie Dimon. Some thought a fall guy (or gal) would be found. But the idea that everyone would walk away seemed impossible.

Ten months later, customers are still fighting for their money to be returned, and getting it in pennies rather than pounds. (A recent ruling will return $130 million more from the CME Group (NYSE: CME).) JPMorgan Chase is onto its next scandal involving customer accounts and the collapse of a brokerage firm. And Corzine, whose hands-on role at MF Global included roaming the trading floors, is considering starting a hedge fund.

...you'll just have to be a horrible warning."
 If the collapse of MF Global were a movie, it would be one of those franchises that never ends, because bank scandals aren't unusual, and investigations are far from rare. Barclays (NYSE: BCS) has recently been fined for rigging LIBOR. HSBC (NYSE: HBC) was recently cited and fined for allowing terrorist groups to launder money. The list goes on and on. But more often than not, investigations, when they occur, are essentially an exercise in futility. In cases of guilt, fines, not prosecutions, are levied, even in cases where international laws are broken.

According to a chart by The New York Times, prosecution for bank fraud has fallen dramatically over the past four administrations, even while it seems that wrongdoing by large banks is on the rise, from mortgage robo-signing to hidden fees on credit cards, to fraudulent insurance products.

Stay tuned
 I'll have continuing coverage of the MF Global investigation, including what charges could still be pressed, and at what level. Because, despite recent developments, this case will not go away quietly. Trustee James Giddens has agreed to help the lawyers of customers suing MF Global executives for damages. Koutoulas has vowed to pursue Corzine using all resources available.

As we look forward, perhaps there's no better advice than that given by a certain ex-New Jersey Governor turned financial punch line. "You can't just look at what is good in the moment, what feels good, what works for today may not be the answer that actually helps ... two years down the road or five years down the road. You have to make decisions with a longer-term perspective." So said Jon Corzine.

But I much prefer the quote by author Catherine Aird: "If you can't be a good example, you'll just have to be a horrible warning." Because the days of good examples are long gone, and horrible warnings have just begun.

What do you think? Should criminal charges be pressed against MF Global executives? Are fines enough for large banks found breaking the law? Tell me in the comments box below.