campaign associates. cnn is told investigators combed through the list of shell companies and trump branded process. reaching back several years. and officials familiar with the investigation tell cnn special counsel robert mueller's team has examined the becoming of russian business associates connected to trump. getting back to the 2013 miss universe pageants he hosted in moscow. >> thank you for their amazing hospitality. >> reporter: cnn couldn't determine whether the review included trump's tax returns. but even investigative leads that have nothing to do with russia but involve trump associates are being referred to the special counsel to encourage subjects of the investigation to cooperate. >> the entire thing has been a witch-hunt. >> reporter: president trump keenly aware of the increased