The source says that Deutsche Bank is in possession of loan documents that show Donald Trump has obtained loans with co-signers, and that he would not have been able to obtain loans without cosigners. The source says that the cosigners...are Russian billionaires cclosd to                                                                                                                                                                                                                                                                                                                                                                       cse to Vladimir Putin.

• This is a single source inside Deutsche Bank.
• That source has not been vetted by anyone other than O'Donnell's team at MSNBC.
• If loans co-signed by oligarchs actually exist, the FBI has known about them for a while. It's difficult to understand how it would be appropriate to conclude the Mueller investigation without some explication of these relationships.
• It's too perfect. Billionaire oligarchs personally co-signing loans? Really?

• Why Deutsche Bank, Trump's Last Lender, Kept Lending through Repeated Defaults - Since the late 2000s, DB was the last western bank willing to bankroll him, which was especially strange in light of his history specifically with stiffing Deutsche Bank and suing them in court. No one knows why they were willing to repeatedly accept the considerable risk Trump entailed, but given Deutsche's prolific history of Russian money laundering, the big question was whether those loans were being backstopped through other sources.
• Trump's Bizarre Golf-Heavy Spending Spree - From 2006-2015, Trump Org went on a mysterious all-cash spending spree. The biggest purchases were in 2010-2014, precisely aligning with Deutsche's heaviest period of Russian money laundering, and precisely the time that Eric Trump contemporaneously explained to golf writer that all of their financing was coming from Russia.

I said, ‘Eric, who’s funding? I know no banks—because of the recession, the Great Recession—have touched a golf course. You know, no one’s funding any kind of golf construction. It’s dead in the water the last four or five years.’ And this is what he said. He said, ‘Well, we don’t rely on American banks. We have all the funding we need out of Russia.’ I said, ‘Really?’ And he said, ‘Oh, yeah. We’ve got some guys that really, really love golf, and they’re really invested in our programs. We just go there all the time.’

• Deutsche Bank's Freakout When Trump wins Election - Right before the election, Trump was predictably having a hard time with the scottish golf courses (which were objectively awful investments that continue to lose money) and needed a bailout. This is when Deutsche Bank appears to have finally realized the gravity of the situation, and denied his loan request, even though it was to just be an extension of loans for his (at the time, profitable) Doral property. Then when he actually won and Russia's election assistance was revealed, they raced to unload a considerable $600 million loan to VTB (the originally planned financier for Trump Tower Moscow). The loan had no documented purpose in DB's records.
• Trump's Subordination to Putin: "Sistema" - There is some explanation for why Trump's sycophancy towards Vladimir Putin, most egregiously in Helsinki last year. There is some explanation for why he insists on periodic, private meetings where he destroys all records of what was discussed afterwards. Nervousness over conspiracy in the election was always a plausible explanation, but never the most likely. More plausible is simply that Trump unwittingly bumbled himself into becoming part of the Russian "Sistema", the structure by which Russian oligarchs are forced to stay in line (and subservient to Putin) because they all understand thay they have mutually benefited from criminal activity, and can be destroyed by it's exposure. As described by the New Yorker's Adam Davidson in A Theory of Trump Kompromat:

Each actor in sistema faces near-constant uncertainty about his status, aware that others could well destroy him. Each actor also knows how to use kompromat to destroy rivals but fears that using such material might provoke an explosive response. While each person in sistema feels near-constant uncertainty, the over-all sistema is remarkably robust. Kompromat is most powerful when it isn’t used, and when its targets aren’t quite clear about how much destructive information there is out there. If everyone sees potential land mines everywhere, it dramatically increases the price for anybody stepping out of line.