when abc news went to the headquarters of puda coal in china, we were told the chairman had not beenhat no one at the office knew his whereabouts. >> do you know when he'll be back? >> that's amazing. that's amazing. how can he not at least be under some prosecution for this? >> reporter: puda coal was one of the many chinese companies that the new york stock exchange and nasdaq began to aggressively recruit back in 2008, seeing the potential for big profits. nasdaq executive went on cnbc to make his pitch for new listings. >> we think there's no better place to find them than in china. >> reporter: but officials say again and again the stock exchanges in their rush to get the chinese business, did a poor job of verifying the financial health of the companies. >> i think there was a time when they were not as rigorous as they could have been. >> reporter: also coming under scrutiny by the s.e.c. are several big american auditing firms, with chinese subsidiaries. as well as the american middle men who promoted the chinese companies with often elaborate presentations. >> those are all