Prosecutors granted immunity to an ex-girlfriend of Representative Matt Gaetz before she testified last week in front of a federal grand jury hearing evidence in the investigation of the congressman, according to a source familiar with the matter.

The woman, who CBS News is not naming to protect her privacy, testified in front of a federal grand jury in Orlando last Wednesday.

Isabelle Kirshner, an attorney for Gaetz, told CBS News in a statement last week that "we have seen no credible basis for a charge against Congressman Gaetz

A source told CBS News last week that as a part of an obstruction probe, investigators are looking into whether Gaetz had a phone call with the ex-girlfriend, and another woman, who was already a witness in the federal investigation. 

Multiple sources told CBS News that the ex-girlfriend and the other woman traveled to the Bahamas with Gaetz in 2018, along with a third woman with whom Gaetz was in a sexual relationship

Two sources familiar with the matter told CBS News it was Joel Greenberg, a former Florida county tax collector and associate of Gaetz's, who introduced Gaetz to that woman when she was 17 years old