Investigation The police assumed that an anarchist had thrown the bomb as part of a planned conspiracy; their problem was how to prove it. On the morning of May 5, they raided the offices of the , arresting Spies and his brother, who was not charged. Also arrested were editorial assistant Michael Schwab and Adolph Fischer, a
typesetter. A search of the premises resulted in the discovery of the "Revenge Poster" and other evidence considered incriminating by the prosecution. On May 7, police searched the premises of
Louis Lingg where they found bombs and bomb-making materials. Lingg's landlord William Seliger was also arrested but cooperated with police, identified Lingg as a bomb-maker, and was not charged. An associate of Spies, Balthazar Rau, suspected as the bomber, was traced to
Omaha and brought back to Chicago. After interrogation, Rau offered to cooperate with police. He alleged that the defendants had experimented with dynamite bombs and accused them of having published what he said was a code word, "Ruhe" ("peace"), in the as a call to arms at Haymarket Square.
Defendants Rudolf Schnaubelt, the police's lead suspect as the bomb thrower, was arrested twice early on and released. By May 14, when it became apparent he had played a significant role in the event, he had fled the country. William Seliger, who had
turned state's evidence and testified for the prosecution, was freed by the state. On June 4, 1886, eight other suspects were indicted by the
grand jury and stood trial for being
accessories to the murder of Degan. Of these, only two had been present when the bomb exploded. Spies and Fielden had spoken at the peaceful rally and were stepping down from the speaker's wagon in compliance with police orders to disperse just before the bomb went off. Fischer and Parsons had been present at the beginning of the rally but had left and were at Zepf's Hall, an anarchist rendezvous, at the time of the explosion. Parsons, who believed that the evidence against them all was weak, subsequently voluntarily turned himself in, in solidarity with the accused. Of the eight defendants, Spies, Fischer, Engel, Lingg and Schwab were immigrants born in Germany; Neebe, was a U.S.-born citizen of German descent. Parsons and Fielden, born in the U.S. and England, respectively, were of British heritage. It was presided by Judge
Joseph Gary, who displayed open hostility to the defendants, consistently ruled for the prosecution, and failed to maintain
decorum. A motion to try the defendants separately was denied. The defense counsel included
Sigmund Zeisler and
William Perkins Black.
Selection of a jury was extraordinarily difficult, lasting three weeks, and nearly 1,000 people had been called. All union members and anyone who expressed sympathy toward socialism were dismissed. In the end a jury of 12 was seated, most of whom confessed prejudice against the defendants. Despite their professions of prejudice Judge Gary seated those who declared that despite their prejudices they would acquit if the evidence supported it, refusing to dismiss for prejudice. Eventually the peremptory challenges of the defense were exhausted. Frustrated by the hundreds of jurors who were being dismissed, a
bailiff was appointed who selected jurors rather than calling them at random. The bailiff proved prejudiced and selected jurors who seemed likely to convict based on their social position and attitudes toward the defendants. The jury heard the testimony of 118 people, including 54 members of the Chicago Police Department and the defendants Fielden, Schwab, Spies and Parsons. Albert Parsons's brother claimed there was evidence linking the Pinkertons to the bomb. This reflected a widespread belief among the strikers.
Verdict and contemporary reactions The jury returned guilty verdicts for all eight defendants. Before being sentenced, Neebe told the court that Schaack's officers were among the city's worst gangs, ransacking houses and stealing money and watches. Schaack laughed, and Neebe retorted, "You need not laugh about it, Captain Schaack. You are one of them. You are an anarchist, as you understand it. You are all anarchists, in this sense of the word, I must say." Judge Gary sentenced seven of the defendants to death by hanging and Neebe to 15 years in prison. The sentencing provoked outrage from labor and workers' movements and their supporters, resulting in protests around the world, and elevating the defendants to the status of
martyrs, especially abroad. Portrayals of the anarchists as bloodthirsty foreign fanatics in the press along with the 1889 publication of Captain Schaack's sensational account,
Anarchy and Anarchism, on the other hand, inspired widespread public fear and revulsion against the strikers and general anti-immigrant feeling, polarizing public opinion. In an article datelined May 4, entitled "Anarchy's Red Hand",
The New York Times describes the incident as the "bloody fruit" of "the villainous teachings of the Anarchists". The
Chicago Times described the defendants as "arch counselors of riot, pillage, incendiarism and murder"; other reporters described them as "bloody brutes", "red ruffians", "dynamarchists", "bloody monsters", "cowards", "cutthroats", "thieves", "assassins", and "fiends". Journalist George Frederic Parsons wrote a piece for
The Atlantic Monthly in which he identifies the fears of
middle-class Americans concerning labor radicalism and asserts that the workers had only themselves to blame for their troubles.
Edward Aveling remarked, "If these men are ultimately hanged, it will be the
Chicago Tribune that has done it." Schaack, who had led the investigation, was dismissed from the police force for allegedly having
fabricated evidence in the case but was reinstated in 1892.
Appeals The case was
appealed in 1887 to the
Supreme Court of Illinois, then to the
United States Supreme Court where the defendants were represented by
John Randolph Tucker,
Roger Atkinson Pryor, General
Benjamin F. Butler and
William P. Black. The petition for
certiorari was denied.
Commutations and suicide After the appeals had been exhausted, it was left to Illinois Governor
Richard James Oglesby to decide whether to
commute the sentences of the convicted. Hundreds of thousands of people across the country petitioned him to do so, though the press at the time largely called for executions. Oglesby was troubled by the case. Parson's attorney had noted in the trial that hanging these men would be the equivalent of hanging
abolitionists who had sympathized with
John Brown. Oglesby, a former
Radical Republican, acknowledged that under these laws "all of us abolitionists would have been hanged a long time ago". In the end, Oglesby decided he would only pardon those who asked for clemency. Four of the seven outright refused this on the grounds that they had committed no crime, and so only the two who did request mercy, Fielden and Schwab, had their sentences commuted to life in prison on November 10, 1887. On the eve of his scheduled execution, Lingg died by suicide in his cell with a smuggled
blasting cap which he reportedly held in his mouth like a cigar (the blast blew off half his face, and he survived in agony for six hours).
Executions The next day (November 11, 1887) four defendants—Engel, Fischer, Parsons, and Spies—were taken to the
gallows in white robes and hoods. They sang the , the anthem of the international revolutionary movement. Family members including
Lucy Parsons, who attempted to see them for the last time, were arrested and searched for bombs (none were found). According to witnesses, in the moments before the men were hanged, Spies shouted, "The time will come when our silence will be more powerful than the voices you strangle today." In their last words, Engel and Fischer called out, "Hurrah for anarchism!" Parsons then requested to speak, but he was cut off when the signal was given to spring the trap door. Witnesses reported that the condemned men did not die immediately when they dropped but strangled to death slowly, a sight which left the spectators visibly shaken. Historians such as
James Joll and
Timothy Messer-Kruse say the evidence points to Schnaubelt as the likely perpetrator. ==Pardons and historical characterization==