“The Judiciary Committee will talk to Trump Jr. & Manafort before they testify in public, but we will get answers.”
"...The two lawmakers also announced they have issued a subpoena for Fusion GPS co-founder Glenn Simpson. Fusion GPS, Simpson’s research firm, commissioned the infamous Trump-Russia dossier compiled by a former British spy.
“Glenn Simpson, through his attorney, has declined to voluntarily attend Wednesday’s Judiciary Committee hearing regarding compliance with the Foreign Agents Registration Act,” the statement read. “Therefore, a subpoena has been issued to compel his attendance.”
http://www.huffingtonpost.com/entry/trump-jr-manafort-agreement-senate-hearing_us_5972c9c6e4b0e79ec1996727