Attorney General William Barr is looking into the murky origins of the politically charged Justice Department investigations that have roiled American public life for the last three years.

Just how did the FBI’s “Crossfire Hurricane” investigation into the 2016 Trump presidential campaign get started? What led the FBI to look into whether President Trump was working on behalf of Russia? Why did the Justice Department use an ancient, never-enforced law as a pretext to interrogate then-national security adviser Michael Flynn, leading to one of the most troubling court cases in recent years? And more.