On September 16, 1897, in the streets of Mexico City, the then president of the Republic, Porfirio Diaz, was attacked by a man. The event did not go beyond a brief physical blow to the then-president. However, the corresponding action of the authorities revealed the extrajudicial state that was applied by the Porfirian regime.

As part of the Independence Day celebrations, President Porfirio Díaz had to go, along with his entourage, to the Alameda Central where a remembrance to the heroes of the homeland would take place. Amid a crowd composed of diverse social classes from the wealthiest to the people forgotten by the regime, the President of the Republic made his way through the human fence formed by the cadets of the Military College.

Unexpectedly, one person managed to evade the military siege. It was Arnulfo Arroyo, who threw his fist directly at Diaz's head. The latter did not manage to dodge the blow. Immediately, several people accompanying the president threw themselves to stop the aggressor, even Brigadier Angel Ortiz Monasterio smashed his cane on the suspect's head.

The situation became increasingly rough for Arnulfo Arroyo, who kept receiving blows and insults. The atmosphere had to be calmed down by the President of the Republic himself, who after recovering ordered to stop all attacks against his aggressor and to proceed immediately to his transfer to be presented to the corresponding authorities.

However, at that moment a series of irregularities began since the officers did not know before which instance to proceed to secure him and initiate the corresponding process, whether civil or military. As such, the Inspector General of Police, Eduardo Velázquez, together with an insignificant number of gendarmes decided to transfer Arnulfo Arroyo to a cell in the Mexico City City City Hall Palace. This happened despite recognizing the danger the suspect was in. Also, during his detention, Arnulfo was handcuffed, gagged, and possibly threatened by Velázquez himself.

The only interrogation that could be collected was conducted by Colonel Generoso Guerrero, 4th Judge of Military Instruction, who identified Arroyo as a single individual, 30 years old, a native of Tlanepantla, and a law student. Likewise, he obtained from the declarant the motives that had led him to attack the President of the Republic, confessing that he had "ideas entirely contrary to the current system of Government that governs the Mexican Nation since he wants another form of Government". Furthermore, "the misery in which he found himself made him desperate".

Once this first statement was obtained, Colonel Generoso Guerrero withdrew without taking any steps to transfer the suspect to a much safer place or to guarantee his integrity. Therefore, Arroyo remained in the cell of the offices of the Inspector General of Police. That night when the fireworks started, Inspector Velazquez, after celebrating and drinking, showed the detainee to all his guests.

Around ten o'clock at night, Inspector Velazquez met with two of his main collaborators: Major Manuel Bellido and policeman Antonio Villavicencio. Together they agreed to assassinate Arroyo and pass it off as a lynching. In the early morning of September 17, a group of henchmen nicknamed the tigers -all gendarmes from the office of the 2nd Police Inspectorate- were led by Villavicencio to storm the cell where Arnulfo Arroyo was being held, who was cruelly murdered.

Not satisfied with the bloodshed that had taken place that night in the Municipal Palace, the Mexico City police began to arbitrarily arrest all the curious who had approached; some officers had fired detonations to encourage the commotion. About twenty innocent people, including children, youths, and adults, had been presented by the authorities as suspects in the lynching of Arnulfo Arroyo, while the main intellectual authors were celebrating with dinner.

In the morning, the newspapers of Mexico City published the official version that had been founded by the police in which the main culprit was the people. But this statement was extremely scandalous for the capital's authorities, who were incompetent for not being able to prevent a lynching inside the Municipal Palace and even arrest the murderers on the spot.

Faced with such a situation, the Porfirian State was not willing to accept a weak image of its authorities, much less in the capital of the country. Thus, Inspector Velázquez was dismissed and apprehended, along with his accomplices, for the murder of Arnulfo Arroyo.

Eduardo Velázquez ended up committing suicide in his cell with a revolver that had been smuggled in, possibly putting himself before the justice that the Porfirian State had prepared for him, that which was characterized by episodes such as "Kill them in the heat of the moment".

The other accomplices such as Villavicencio and the gendarmes known as the tigers were sentenced to capital punishment. This was revoked for a maximum sentence, which was soon forgotten. Arroyo's murderers managed to obtain their freedom, and some were even reinstated in the Mexico City police system. Such was the case of Antonio Villavicencio, who became one of the main enforcers of the Porfirian State. Since then, the documents kept in the Library-Hemerotheque "Ignacio Cubas" of the AGN have been an obligatory source of reference for the multiple efforts to interpret the deep meaning of this crime.