[ticking] >> anton valukas was the man in charge of investigating the collapse of lehman brothers, the fourth-largest investment bank in the world. >> isn't the government supposed to protect the investors? >> yes. >> aren't they charged with informing investors? >> yes. >> why didn't they do it? >> welcome to 60 minutes on cnbc. i'm bob simon. even though fraud played a significant role in the 2008 meltdown of the american economy, as of late 2012, there have been several civil suits filed against major wall street financial firms, but not a single criminal prosecution. in this edition, we look back at the 2008 financial crisis and the failure of government regulators to prosecute those who might be criminally responsible. later, lehman brothers bankruptcy investigator anton valukas shares his findings on the collapse of the giant investment bank where no senior official has ever faced charges in the biggest bankruptcy in u.s. history. but first we begin with a nine-month 60 minutes investigation looking for wall street cases that might have prosecutorial merit. in december 2011, stev

[ticking] >> anton valukas was the man in charge of investigating the collapse of lehman brothers, the