The cooperation of Greenberg and the former girlfriend could be among the final steps in the probe of Gaetz. Investigators view both as crucial to understanding the relevance of hundreds of transactions they have obtained records of, including those involving payments for sex, sources familiar with the investigation tell CNN. The ex-girlfriend could also be questioned by investigators about a second woman as they try to determine whether Gaetz may have slept with that woman when she was only 17. The former girlfriend, who did not work in Gaetz's office on Capitol Hill, is of interest to investigators because she was on a trip Gaetz took to the Bahamas in 2018 and is believed to have knowledge of drug use and arrangements with women, the sources say. Gaetz has been isolated politically but has remained defiant in the six weeks since the investigation first became public, launching a nationwide speaking tour alongside the controversy-generating Georgia Republican, Rep. Marjorie Taylor Greene, with the investigation swirling around him.