The Justice Department secretly took steps in 2017 to narrow the investigation into Russian election interference and any links to the Trump campaign, according to former law enforcement officials, keeping investigators from completing an examination of President Trump’s decades-long personal and business ties to Russia.
The special counsel who finished the investigation, Robert S. Mueller III, secured three dozen indictments and convictions of some top Trump advisers, and he produced a report that outlined Russia’s wide-ranging operations to help get Mr. Trump elected and the president’s efforts to impede the inquiry.
But law enforcement officials never fully investigated Mr. Trump’s own relationship with Russia, even though some career F.B.I. counterintelligence investigators thought his ties posed such a national security threat that they took the extraordinary step of opening an inquiry into them. Within days, the former deputy attorney general Rod J. Rosenstein curtailed the investigation without telling the bureau, all but ensuring it would go nowhere.