George Papadopoulos falls under new investigation for alleged business ties to Russia -- after the 2016 election

Former Trump campaign adviser George Papadopoulos has fallen under new investigation -- and a reporter who helped break the story explains the latest revelations.

Papadopoulos was released earlier this month after serving 12 days in prison for lying to FBI agents, and he announced an intention to run for Congress in 2020, but Atlantic reporter Natasha Bertrand described a letter she obtained that may have launched a fresh look at his activity shortly after the 2016 election.

"This was written by a former confidant of George Papadopoulos who has come forward to the House Intelligence Committee and to the FBI," Bertrand told MSNBC, "to say she has information about his alleged interactions after the election that may have had ties to Russian officials and he was trying to do some big business deal that would, quote-unquote, set himself up for life."

Bertrand and investigative reporter Scott Stedman said investigators want to interview the letter's author about those claims.

"They want to understand whether or not George Papadopoulos' ties to Russia are deeper than previously understood," she said. "Of course, he's a central figure in the Russian investigation."

She said Papadopoulos, who raised eyebrows when Trump named him as a foreign policy adviser in March 2016, had sought to downplay his role in the campaign -- but she said he was a central figure in the special counsel probe.

"He was the one who essential sparked the entire Russia investigation, according to reporting we have seen," Bertrand said. "His conversations about learning of the Clinton emails that the Russians apparently had in April of 2016 are what prompted the entire FBI probe to begin with."

She said investigators would want to know whether Papadopoulos told the campaign about his possible post-election business dealings with Russia, and whether Trump kept him in his orbit because of those connections -- and not in spite of them.