Peter Navarro, a former trade adviser to President Donald Trump, has been convicted of contempt of Congress for refusing to co-operate with a probe into the 2021 US Capitol riot.
Prosecutors said Navarro acted "above the law" by ignoring a subpoena from a congressional investigation.
He faces up to a year in prison for each of the two contempt counts.
Another Trump ally, Steve Bannon, was convicted of similar charges last year and is free pending appeal.