The US attorney's office in New York is conducting a criminal investigation of Goldman Sachs over mortgage securities deals the big Wall Street firm arranged. The inquiry reportedly stems from a criminal referral by the Securities and Exchange Commission. A source spoke Thursday on condition of anonymity because the investigation is in a preliminary phase. News of the action came a day after a group of 62 House lawmakers, including Judiciary Committee Chairman John Conyers Jr. (D-Mich.), asked the Justice Department to conduct a criminal investigation of Goldman.