[ by Melanie Gretchen ] Former Credit Suisse employee David Higgs surrendered to the FBI on Wednesday on criminal charges, the FBI said, in a U.S. government probe on writedowns on subprime mortgage derivatives at the height of the financial crisis.  Up to 4 former employees of the Swiss bank face criminal or civil charges, people familiar with the investigation said this week. The investigation emerged from $2.85 billion in writedowns that the bank took on collateralized debt obligations (CDOs) in 2008, the sources said, on the condition of anonymity.  Credit Suisse reported those CDO losses in early 2008, attributing them to a group of rogue traders - who the bank said had deliberately mispriced securities - and on a failure of internal controls.  The bank will not be charged in the matter. Higgs was scheduled to appear in U.S. District Court in New York today.  A spokeswoman for the office of the Manhattan U.S. Attorney declined to comment. For more details, go to [Reuters, 2/1/12].