Former Minnesota Republican Rep. Vin Weber is being targeted as part of Special Counsel Robert S. Mueller III’s Russia investigation, sources with direct knowledge of the investigation told The Associated Press.

Weber, who served in the House from 1981 to 1993 and is a partner at lobbying firm Mercury LLC, is being targeted for his firm’s work with former Trump campaign chairman Paul Manafort’s Ukrainian lobbying efforts, the AP reported.

“With the emphasis on the Ukrainian lobbying efforts, Mueller’s criminal probe is moving beyond investigating ties between the Trump campaign and Russia and is aggressively pursuing people who worked as foreign agents without registering with the Justice Department,” the AP reported. “More witnesses are expected before the grand jury in coming weeks.”

FBI agents working for Mueller, himself a former FBI director, are asking witnesses to detail communications with the party of Viktor Yanukovich, the former Ukrainian president and ally of Russian President Vladimir Putin.

Also targeted in the probe is Democratic lobbyist Tony Podesta, who resigned from his firm.