National Security Adviser-designate Michael Flynn walks in the lobby of Trump Tower in New York, Thursday, Jan. 12, 2017. AP Photo/Evan Vucci Russian operatives reportedly boasted during the 2016 election that they could use their relationship with Michael Flynn to make inroads with President Donald Trump and his associates.

The news comes after several days of headlines in which Flynn, who was forced to resign from the Trump administration in February, was the center of the Trump-Russia controversy. CNN first reported Russia's alleged boasting about Flynn on Friday night, describing it as "a five-alarm fire" in the eyes of law enforcement "from very early on."

The network cited unnamed sources who said that the Russians saw Flynn as an ally. At least two other former Trump associates, Paul Manafort and Carter Page, are under FBI investigation for their ties to Russia. A senior White House official is now caught up in the FBI's Russia probe, too, McClatchy reported on Friday.

The Obama administration had been skeptical of Flynn, who is under criminal investigation by the FBI for his foreign contacts and payments, since last year. President Barack Obama warned Trump against hiring him in November, but Trump hired him anyway — even after Flynn informed Trump's transition team that he was being investigated by the FBI over his lobbying work for Turkey, according to The New York Times.

(A White House spokesman told Business Insider on Thursday that the Times story "is flat wrong. Neither Michael Flynn nor his attorneys told Transition Counsel ‘that he was under federal investigation for secretly working as a paid lobbyist for Turkey during the campaign.’”)

Flynn's previous appearances on, and payments from, Russian state media — including an event in which he appeared sitting next to Russian President Vladimir Putin — were also seen as red flags. Flynn agreed to testify before the House and Senate intelligence committees in late March in exchange for immunity from prosecution, but neither committee has agreed so far.

Flynn's time at the White House lasted just 24 days. He was asked to resign on February 13 over reports that he had discussed sanctions with Russia's ambassador to the US, Sergey Kislyak, during the transition. But Trump continued to defend him, going as far as suggesting to FBI Director James Comey the next day to drop the investigation into Flynn's foreign contacts, according to a memo Comey wrote about the conversation.

Comey wrote memos documenting the conversation because he felt Trump's advances were inappropriate, according to the New York Times.

Yahoo News reported on Thursday, moreover, that Trump has stayed in contact with Flynn, urging him to "stay strong" in a private message in April. White House aides told The Daily Beast that Trump wanted to bring Flynn back into the administration.

The many controversies surrounding Flynn raise further questions about why Trump was so determined to bring him into his Cabinet and overlook his considerable baggage, which included including a falling-out with the Defense Intelligence Agency and his lobbying work for a Dutch firm linked to Turkey's government throughout the end of 2016.

"Trump's team knew about [Flynn's] ties to Russia and they knew about his work with Turkey," said Rep. Eric Swalwell, a Democrat who sits on the House Intelligence Committee. "What's most concerning is that it looks like they just didn't care. So you have to ask yourself — were Flynn's prior relationships an asset?"

Congressional lawmakers have asked Flynn for documents related to their Russia-related inquiries, but Flynn has not yet responded to those requests.