Robert Costello, a former legal adviser to Michael Cohen, is set to testify before a Manhattan grand jury on Monday in an investigation into Donald Trump's alleged "hush money" payment to Stormy Daniels. Trump's attorneys have asked the District Attorney for Costello to testify, and two sources confirmed to CBS News that Cohen has been asked to be available in case he's needed to "rebut" another witness. It is unclear what information Costello will provide to the grand jury and what impact his testimony will have on the investigation.
