Donald Trump's Russian connections, coupled with his frequent support for Russian President Vladimir Putin, have been the subject of scrutiny for months, but just yesterday, a series of parallel controversies came into focus.The lines between the stories can get a little blurry, so let's try to clarify matters.Controversy #1: FBI scrutiny of Russian hackingAs we discussed yesterday, there's some evidence that the FBI recently reached an important conclusion: Russian hackers did, in fact, steal Democratic materials in the hopes of helping Trump win the U.S. presidential election. The FBI didn't tell the public, however, because Director James Comey believed the revelations came too close to Election Day (a concern he didn't apply to the Democratic candidate for reasons that are unclear).Controversy #2: FBI takes an interest in Trump's former campaign chairmanNBC News reported late yesterday that the FBI "has been conducting a preliminary inquiry into Donald Trump's former campaign manager Paul Manafort's foreign business connections," including connections in Russia and Putin's allies in Ukraine. Manafort has denied any wrongdoing.Controversy #3: The Trump Organization's serverFranklin Foer published a piece in Slate on the findings of computer scientists, who found something unexpected: the Trump Organization had a server that had a series of suspicious, exclusive transmissions with a Russian bank operated by Putin's oligarch allies. When a reporter began inquiring about the connection, the transmissions stopped without explanation.Controversy #4: David Corn's foreign sourceMother Jones' David Corn reported late yesterday that "a former senior intelligence officer for a Western country who specialized in Russian counterintelligence" told him a doozy of a story: the unnamed officer says he provided the FBI with "memos, based on his recent interactions with Russian sources, contending the Russian government has for years tried to co-opt and assist" Donald Trump. The report added that the FBI "requested more information from him."It's worth emphasizing that Trump and his team have denied any wrongdoing, and not all of the reporting points in an alarming direction. The New York Times, for example, reports today that the FBI has scrutinized the Republican team's connections to Russia, and at least for now, "none of the investigations ... found any conclusive or direct link between Mr. Trump and the Russian government."Of course, given the broader circumstances, we don't know who's responsible for leaking this to the Times or what political motivations may be at play.Whether anything will come of these allegations is unclear, and it's entirely possible that we're looking at smoke without a fire. But the allegations themselves are nevertheless serious and worth exploring in the campaign's final week.