"I'm mad! I'm mad!" Lewis Powell shouted as he burst out of the Secretary of State's house, threw himself on his horse, and rode away. Across town, Abraham Lincoln slumped forward in his theater chair, a laugh forever frozen on his face.

The year was 1865, and the scene at Ford's Theatre was the end of a President and the beginning of a legend. But many have forgotten that Lincoln's assassination was just one facet of a three-pronged plot to take down America—and fewer still know about the mysterious Confederate deserter who became John Wilkes Booth's right-hand man.

Was he a member of the Confederate Secret Service? A soldier who used a Union soldier's skull as an ashtray? A suave city man, or a country Baptist with a simple mind? During 21 years of life and countless aliases, Lewis Powell adopted all of these identities and more. After deserting the flailing Confederate Army, Powell met John Wilkes Booth, one of the most famous actors of his day, in a Baltimore hotel. Over dinner, Booth recognized a kindred spirit. He immediately recruited Powell to the cause that obsessed him: his plan to kidnap President Lincoln in retribution for his political views.

From that day forward, the two men became extremely close and worked together on their plot. They even watched Lincoln's last speech ever, one about reconstruction, from the White House lawn. Angered, the conspirators knew kidnapping was not enough. They decided they must murder the President in order to bring down the entire American government.

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The conspiracy that followed revolved around three simultaneous acts of violence calculated to create chaos and fear in the Union government and punish Booth's enemies for their roles in the bloody war that was ending. While Booth killed Lincoln at Ford's Theatre, Powell would murder Secretary of State William H. Seward, and George Atzerodt, another conspirator, would shoot Vice President Andrew Johnson. But the plot went wrong from the start. Atzerodt, overcome by fear, could only get as far as the hotel bar where Johnson was staying (he drank all night, but never shot the vice president).

On the night of April 14, Powell and another conspirator, David Herold, made their way to the Secretary of State's residence. Seward was inside, recovering from a concussion, broken jaw, and other injuries following a recent carriage accident. Powell entered Seward's house pretending to deliver medicine while Herold waited out front. Powell pushed his way past Seward's butler, who ran into the night to get help. This frightened Herold, who immediately took off.

Once inside, Powell attempted to shoot Seward's son Frederick, but his revolver misfired. Powell beat him to the floor and made his way to the room where Seward was recovering. The Secretary of State was being tended to by his daughter and by Sergeant George F. Robinson, an army nurse. Powell slashed Robinson and punched Seward's daughter in the face. He then climbed atop Seward and stabbed and slashed at his head and neck. Because of his injuries from the carriage accident, Seward was wearing a metal splint around his jaw. This protected him from any would-be fatal blows, but Powell managed to slash his cheek and face. Though he survived the attack, the scars would remain with Seward for life.

Seward's other son Augustus burst into the room and wrestled with Powell. Powell slashed at Augustus and got away, but not before encountering a messenger in the hallway (who Powell stabbed, as well). Powell escaped, but he was a stranger on the run in Washington, D.C. Helpless without Herold, he disappeared for three days, wandering the streets or hiding alone. Finally, he returned to the boarding house where Booth and the other conspirators rendezvoused before the assassination. As he got there, police were taking the owner of the house and others away for questioning. Powell claimed he was just a laborer there to dig a gutter, but the police were suspicious because he was wearing expensive clothing, so they took him into custody when he was positively identified.

Powell's well-kept hands are in shackles in this photograph Alexander Gardner took after his arrest. Powell looks easy-going, relaxed, and strangely modern for a man on the wrong side of history.

By the time Powell was transferred to a monitor ship by the authorities, John Wilkes Booth was dead. Two months later, Powell was found guilty of conspiracy and hanged. During his time in chains, he reportedly told tall tales about his Confederate days, chewed tobacco, and attempted suicide by bashing his head into the walls of his cell. Despite his behavior, doctors refused to acknowledge he was insane.

On July 7, 1865, he was hanged alongside Mary Surratt (the owner of the rendezvous point), David Herold, and George Atzerodt.

But the strange case of Lewis Powell didn’t end there. Like those of his co-conspirators, Powell's corpse was cast into a coffin and temporarily buried. Years later, the four bodies were released to their families. There are multiple assertions that no one showed up to claim Powell's. Others maintain that his family had taken some of his remains. Either way, no one knows where his remains are, except for his skull, which popped up in a most unlikely place.

In 1991, Lewis Powell's skull was found in the Native American collection at the Smithsonian Museum. After some research, it was confirmed as his. It sat there for over a century.

References: The Orlando Sentinel, "Mystery Still Shrouds Story Of Lewis Powell" by Jim Robinson (July 5, 1992); Alias "Paine": Lewis Thornton Powell, the Mystery Man of the Lincoln Conspiracy, by Betty J. Ownsbey (McFarland, 2005); Blood on the Moon: The Assassination of Abraham Lincoln, by Edward Steers (University Press of Kentucky, 2005); American Brutus: John Wilkes Booth and the Lincoln Conspiracies, by Michael W. Kauffman (Random House, 2005); The Lincoln Assassination Encyclopedia, by Edward Steers (Harper Perennial, 2010)