McKinley smiled and extended his hand...

Leon Czolgosz in custody

On this day in 1901 the anarchist Leon Czolgosz assassinated President William McKinley. From History's The Assassination of President William McKinley:

Despite the sweltering late-summer heat, a long line of people waited outside the Temple of Music when the reception began at 4 p.m. As the theater’s organist played a Bach sonata, the visitors slowly filed inside, many of them eager for a chance to meet the president and shake his hand. Near the front of the line stood 28-year-old Leon Czolgosz, a shy and brooding former steel worker. An avowed anarchist, Czolgosz had arrived in Buffalo only a few days earlier and purchased a .32 caliber Iver Johnson revolver—the same type of weapon that another anarchist had used to assassinate the Italian King Umberto I the previous summer. He now waited with the gun wrapped in a white handkerchief and concealed inside his jacket pocket. “It was in my heart; there was no escape for me,” Czolgosz later said. “All those people seemed bowing to the great ruler. I made up my mind to kill that ruler.”

McKinley’s anxious staff had added police and soldiers to his usual complement of Secret Service agents, but the security detail took little notice of Czolgosz as he strode up to the president at around 4:07 p.m. When McKinley smiled and extended his hand, Czolgosz raised his pistol—still wrapped in its white handkerchief—and fired two shots at point blank range. 

The above picture is of Czolgosz in Buffalo's jail. He did not repent his crime, saying in his confession, “I don’t believe in the Republican form of government, and I don’t believe we should have any rulers. It is right to kill them.”

Justice was swift. Czolgosz was tried, found guilty and sentenced to death in short order. He was executed by electric chair on October 29th of the same year as the assassination.