The Department of Justice has added an attorney with expertise in weapons export and sanctions laws to the team prosecuting Maria Butina, the accused Russian agent whose handler was entwined with Kremlin-connected arms manufacturers banned from doing business in the United States.

The addition of Will Mackie brings to three the number of prosecutors pursuing the case against Butina. She faces charges of conspiracy and acting as an unregistered foreign agent for what authorities say was her attempt to gain political influence through the National Rifle Association, part of a broader Russian campaign to install Donald Trump in the White House.

Mackie, an assistant U.S. attorney in the Justice Department’s National Security Division, has spent years prosecuting violations of U.S. sanctions and international arms embargoes. In 2008, he helped win a guilty verdict in the high-profile case against John Reece Roth, a University of Tennessee professor who passed secret military data to research assistants from China and Iran. More recently, Mackie was involved in the controversial prosecution of Marc Turi, an Arizona arms dealer who sought to sell sniper rifles, machine guns, and other weapons to Libyan rebels during the uprising against Muammar el-Qaddafi. (The charges against Turi were dropped after he reached a civil settlement with the State Department).

Court filings show that Mackie joined the Butina prosecution team days after Senator Ron Wyden, Democrat of Oregon, asked the Treasury Department to investigate possible U.S. sanctions violations by two Russian arms manufacturers. Those manufacturers, Kalashnikov Concern and Tula Cartridge Plant, have ties to Alexander Torshin, a high-ranking Russian official suspected of directing Butina’s spying activities in the United States.

In 2014, Kalashnikov Concern, Russia’s biggest gunmaker, sought to expand its foothold in the American market to shore up its flagging business. But its hopes of using America as a path to revival were dashed later that year when the Obama administration imposed sanctions against the company in response to Russian military involvement in Ukraine. The NRA protested the sanctions, decrying them as a subterfuge for gun control.

Two months later, Butina’s Russian gun-rights organization, the Right to Bear Arms, hosted Paul Erickson, an NRA member and longtime Republican political operative, at the group’s meeting in Moscow.

Another assistant U.S. attorney on the Butina case, Erik Kenerson, was involved this year in the prosecution of Evgeny Spiridonov, a consultant to Kalashnikov Concern who pleaded guilty for violating American export controls after he was caught boarding a Moscow-bound plane in Las Vegas with a high-tech rifle scope in his luggage.