Lloyd Blankfein, the head of Goldman Sachs Group Inc., failed to own up to his firm’s role in selling mortgage securities that helped trigger the global credit crisis, said the chairman of the panel investigating the financial meltdown. “Mr. Blankfein himself never admitted that there was any responsibility of Goldman Sachs to make sure the products themselves were good products,” Philip Angelides, chairman of the Financial Crisis Inquiry Commission, told reporters after a hearing in Washington today. “That’s very troublesome.”