On Aug. 3, 1807, in Richmond, Va., Chief Justice John Marshall opened the trial of former vice president Aaron Burr. The charge: treason against the United States. Burr was accused of plotting an armed insurrection against the government.

More than two centuries later, potential treason is being discussed again following the latest twists in the Justice Department’s investigation of former president Donald Trump, including the revelation that the FBI discovered a top-secret document about a foreign nation’s nuclear capabilities at Trump’s estate in Florida. Former federal prosecutor Glenn Kirschner recently said on MSNBC that Trump’s role in igniting “an armed attack on the Capitol … may actually amount to treason.” So far, the Justice Department hasn’t indicated what charges, if any, might result from its probe, though Trump is facing at least eight criminal and civil proceedings.

Only about 30 people have ever been charged with treason in the United States, and Burr was the highest-ranking official to go on trial. By 1807, he was an outcast from both political parties. He had turned off many Democratic-Republicans when, as Thomas Jefferson’s presumed running mate in 1800, Burr had tried to claim the presidency after both men received the same number of electoral votes. Then, as vice president in 1804, Burr shot and killed Federalist Alexander Hamilton in a duel. Burr also presided over the controversial 1805 impeachment trial of Supreme Court Justice Samuel Chase.

After Jefferson won reelection in 1804 with a new vice president, George Clinton, Burr took several trips to the U.S. Southwest and launched the “Burr Conspiracy.” He assembled an armed force, allegedly to capture a part of Mexico (now Texas) from Spain and to take control of New Orleans in the U.S. Louisiana Territory, and then to persuade western states to join an independent nation he would head.

In December 1806, Jefferson warned that “sundry persons” were conspiring to form an illegal military expedition. In January, he named Burr as “a prime mover” of the treasonous conspiracy and said Burr’s guilt was “placed beyond question.” Meanwhile, he pressed Congress to pass what became the Insurrection Act of 1807, which gave the president the authority to send in troops to quell uprisings.

In February 1807, Burr was arrested in Alabama and taken by military guard on horseback about 900 miles to Richmond, then a town of about 6,000 people, of whom more than 2,000 were enslaved. Burr was put under guard at the city’s Eagle Tavern hotel. Public testimony before a grand jury began on May 22 in Richmond’s federal circuit court.