In his letter, Mr. Cummings also said that his staff had been in consultation with the team of Mr. Mueller, who filed a criminal indictment against Mr. Flynn. The staff of the special council asked Mr. Cummings not to make the whistleblower's account public until "they completed certain steps of investigation," he wrote.
According to the account detailed in the letter, the complainant held a conversation on Opening Day with Alex Copson of ACU Strategic Partners, a company that hired Mr. Flynn in 2015 as an advisor to develop a plan to work with Russia to build nuclear power plants throughout the Middle East. Mr. Flynn served as an advisor until June 2016.
During the conversation, Copson told the snitch that "this is the best day of my life" because it was "the beginning of something I've been working on." "Mr. Copson told the complainant that Mr. Flynn had sent him a text message during Mr. Trump's inauguration speech, telling him to tell other people involved in the nuclear project to continue developing their plans.
"This is going to make a lot of people very rich," Copson said.
Attempts to contact Mr. Copson on Wednesday were unsuccessful: Mr. Flynn's attorney declined to comment.  The letter went on to say that "Mr. Copson explained that General Flynn was making sure that the sanctions would be "destroyed". as one of your first business orders and that this would allow the money to start flowing into the project. "
President Obama imposed economic sanctions on Russia in 2014, after Russia's military incursions into Crimea and Ukraine, and again in December to punish Russia for its attempts to disrupt the US presidential election.
] Earlier this year, several plans were circulated to lift Russia's sanctions through the Trump administration, but Mr. Trump finally decided not to repeal the measures, Mr. Flynn lasted only 24 days as a national security adviser before being expelled amidst questions about whether he lied to administration officials about the nature of his phone calls with Mr. Kislyak.
Mr. Cummings sent the letter to the chairman of the House Supervision and Government Committee, Trey Gowdy, a Republican from South Carolina, and asked him to investigate the complainant's claims. The complainant, said Mr. Cummings, is willing to meet Mr. Gowdy if he agrees to protect the identity of the person.
"I did not get the attention of this snitch," said Mr. Cummings. "I tried to advance this investigation without exposing people to personal or professional risks, but the exceptionally troubling accusations in this case, combined with the continued obstruction of the White House and others, have made this step necessary."