serious backlash for some of the things he said on the campaign trail. this morning he could be in hot water for what he said under oath before running for office about his relationship with a convicted felon who once was tied to organized crime. abc's chief investigative correspondent brian ross is here with that story. good morning, brian. >> good morning. with the possible exceptions of george washington and abraham lincoln american politicians have a well established record of outrageous statements and stretching the truth. but in the case of donald trump, his critics now say he crossed a line between stretching the truth and telling lies. trump's statements about muslims and the 9/11 attacks have raised the biggest questions about his truthfulness. including his unsupported and widely denied claim that thousands of arabs in new jersey celebrated after the attacks. >> thousands and thousands of people were cheering as that building was coming down. >> reporter: then trump...

under oath in a civil lawsuit about one of the people who helped develop the trump soho hotel and condominium in new york city. the man on the right with trump at the hotel launch party. felix sater, a twice convicted felon once tied to organized crime and a massive stock scam someone trump maintains he barely knows in his videotaped testimony obtained by abc news trump said he could not even recall what sater looked like. >> if he were sitting in the room right now i really wouldn't know what he looked like. >> reporter: but an abc news investigation found sater, an executive at a real estate company was actively involved in a number of proposed deals with trump. here they were at a gathering in denver in 2005 and in 2010 three years after sater's mob ties became public the trump organization issued sater business cards identifying him as a senior adviser to donald trump with a trump organization e-mail address and phone number. trump's lawyer says sater was an independent broker but...