Maria Butina, the Russian gun rights activist who was charged last month with working as an unregistered agent of the Kremlin, socialized in the weeks before the 2016 election with a former Trump campaign aide who anticipated joining the presidential transition team, e-mails show, putting her in closer contact with President Donald Trump's orbit than was previously known.

Butina sought out interactions with J.D. Gordon, who served for six months as the Trump campaign's director of national security before leaving in August 2016 and being offered a role in the nascent Trump transition effort, said documents and testimony provided to the Senate Intelligence Committee and described to the Washington Post.

The two exchanged several e-mails in September and October 2016, culminating in an invitation from Gordon to attend a Styx rock concert and his birthday party in late October of that year.

Prosecutors have said Butina, 29, who became a graduate student at American University in 2016, attempted to infiltrate the U.S. political system at the direction of a senior Russian official. Her activities came at the same time that, according to U.S. intelligence officials, Moscow was seeking to interfere in the presidential election to help Trump.

During the campaign, Butina asked Trump at a public event in 2015 about his views on Russia and briefly met Donald Trump Jr. at a National Rifle Association meeting in May 2016.

U.S. investigators probing alleged coordination between the Trump campaign and Russia have been examining dozens of contacts between Russians and Trump associates, including Trump Jr., former campaign chairman Paul Manafort and presidential son-in-law Jared Kushner, as well as foreign policy advisers Carter Page and George Papadopoulos.

Gordon, 50, a former naval officer who served as a Pentagon spokesman under President George W. Bush before working on several Republican campaigns, said his contacts with Butina were innocuous and that she networked extensively.

Robert Driscoll, an attorney for Butina, said the e-mails show that Butina was a student eager to network with Americans who shared her interests and no more.

Jay Sekulow, an attorney for Trump, declined to comment.

Prosecutors say an American identified in court documents as "person 1" helped introduce Butina to people who had "influence in American politics." The Post has identified that person as Paul Erickson, a GOP operative from South Dakota with whom Butina was in a romantic relationship.

Erickson wrote to Butina that Gordon was "playing a crucial role in the Trump transition effort and would be an excellent addition to any of the U.S./Russia friendship dinners."