MATTHEW JOHNSON WAS BY TURNS a wheedler and a bully, and he put both of those talents to use in obtaining a confession from John Anthony Copeland. In one account, Copeland's confession was “extorted by threats,” though in another it was “wormed” out of him. In either event – or both – Copeland's resolve quickly buckled. It did not take long for Marshal Johnson to get what the Ohio press later called “his Negro Confession.”

Both Virginia and federal authorities had been eager to implicate leading abolitionists and prominent Republicans in Brown's conspiracy, but Johnson's interests were more parochial. Rather than act as a “mere imitator of Vallandingham,” he took aim not at congressional figures but rather at his local enemies in the Western Reserve. Johnson's first question to Copeland was whether he was “the same person who was indicted last year at Cleveland for rescuing the slave ‘John.’”

The interrogation continued in that vein, as Johnson demanded to know who had supplied Copeland's funds and where he had stayed during his stopover in Cleveland. Copeland admitted that the Plumbs had given him $15 – slightly less than Ralph Plumb later acknowledged – and he named the Sturtevants as his hosts in Cleveland. Johnson demanded more details, and Copeland added that Plumb and both Sturtevants had known where he was going. Johnson pointedly asked whether Charles Langston had conferred with Copeland and Leary in Cleveland. “He did,” replied Copeland, “and knew that I was coming on to John Brown's company.” One more question tied everything back to the rescue, as though Johnson intended to revive the prosecutions: “Did you hear Ralph Plumb, on the day the slave ‘John’ was rescued, urge persons to go to Wellington?” The inquiry had no connection at all to the Harper's Ferry raid, but Copeland answered that he had indeed heard Plumb's instructions “in front of Watson's grocery” in Oberlin.