Marc Short, who was chief of staff to then-Vice President Mike Pence, is cooperating with the House committee investigating the Jan. 6 riot at the Capitol, according to two people familiar with the panel's activities.
"He is," one of the sources said. "So far."
A second source, who confirmed that Short was subpoenaed, said the panel is in the process of assessing what information Short might be able to provide.
For more on this story, go to NBC News.