Río Piedras massacre

The Río Piedras massacre occurred on October 24, 1935, at the University of Puerto Rico in Río Piedras. Local police officers confronted and opened fire on supporters of the Puerto Rican Nationalist Party. Four Nationalist Party members were killed, and one police officer was wounded during the shooting. As a result of this repression, in December 1935, Pedro Albizu Campos, president of the Nationalist Party, announced that it would withdraw from electoral politics while the United States controlled the island.

Prelude to the massacre
In 1931, the U.S.-appointed Governor of Puerto Rico, Theodore Roosevelt, Jr. named Dr. Carlos E. Chardón as Chancellor of the University of Puerto Rico. He was the first Puerto Rican to have this position. In 1935, Chardón initiated a project based on the ideas of Luis Muñoz Marín, who at the time was a Senator in the Puerto Rican legislature and member of the Liberal Party of Puerto Rico. It was known as the Reconstruction of Puerto Rico Project. The plan, which was within the New Deal criteria established by U.S. President Franklin Delano Roosevelt during the Great Depression, was well received and became known as Plan Chardón.

Pedro Albizu Campos, president of the Puerto Rican Nationalist Party, knew that Roosevelt had been implicated as Assistant Secretary of the Navy in helping the Secretary Bernard Fall of the Department of Interior to arrange for private leasing of Navy oil fields, in what became known as the Teapot Dome Scandal of the 1920s. Albizu Campos worried that Plan Chardón would strip Puerto Rico of her natural resources. He believed that Chardón had been placed in charge of the Puerto Rico Reconstruction Administration (PRRA) in order to "Americanize" the university with the support of the Liberal Party. On October 20, 1935, in a political meeting which the Nationalist Party held in the town of Maunabo and which was transmitted by radio, Albizu Campos denounced Chardón, the university deans and the Liberal Party as traitors, saying they wanted to convert the university into an "American" propaganda institution.

On October 23, 1935, a group of students at the university who supported Chardón began to collect signatures for a petition to declare Albizu Campos "Student Enemy Number One." In turn, a protest against the group by the pro-Nationalist faction of students denounced Chardón and the Liberal Party as agents of the United States.

Massacre
On October 24, 1935, a student assembly held at the university declared Albizu Campos as persona non grata. Chardón requested that the governor provide armed police officers on the university grounds, in case the situation turned violent. Two police officers spotted a "suspicious-looking vehicle" and asked the driver, Ramón S. Pagán, and his friend Pedro Quiñones, for identification. A struggle ensued, and the police killed Pagán and Quiñones. The local newspaper, El Mundo, reported on October 25, that the day before observers heard an explosion followed by gunfire; Eduardo Rodríguez Vega and José Santiago Barea were also killed that day.

An eyewitness, Isolina Rondón, testified that she saw the police officers shooting at the victims and heard one police officer screaming "not to let them escape alive." Her testimony was ignored, and no charges were filed against the police officers. The Río Piedras massacre left four men dead.

Casualties
The supporters of the Nationalist Party killed during the shooting were:
 * Ramón S. Pagán - Nationalist Party Treasurer
 * Eduardo Rodríguez Vega
 * José Santiago Barea
 * Pedro Quiñones

A bystander (not a Nationalist) who was also killed:
 * Juan Muñoz Jiménez

Among the wounded were:
 * Dionisio Pearson, who later died of his wounds.
 * One police officer.

Aftermath
Due to the massacre, on December 12, 1935 Albizu Campos announced that the Nationalist Party would withdraw from electoral politics until American control was ended on the island.

At the time of the massacre, the top-ranking, U.S.-appointed police chief on the island was a former U.S. Army Colonel named Elisha Francis Riggs. Since the entire Insular Police took their orders from Riggs, the Nationalists considered him responsible for the massacre. On February 23, 1936, Riggs was assassinated by the Nationalists Hiram Rosado and Elías Beauchamp, both members of the Cadets of the Republic, a quasi-military youth organization affiliated with the Nationalist Party. They attacked the police chief while he was returning home after attending mass in San Juan's Cathedral. Rosado and Beauchamp were arrested and executed at the police headquarters in San Juan without a trial. Before his death, Beauchamp posed with a military salute for a news photographer.

News of the assassination spread throughout the United States. The Puerto Rican Senator, Luis Muñoz Marín, who was in Washington, D.C. at the time, was asked by Ernest Gruening, the administrator of the Puerto Rico Reconstruction Administration (1935–1937), to condemn Riggs' assassination. Muñoz Marín declined, unless he was also allowed to condemn the police for murdering Nationalists in a city police station without a trial.

Gruening joined U.S Senator Millard Tydings from Maryland, a Democrat, in a 1943 legislative proposal to grant independence to Puerto Rico. Although the measure was welcomed by every political party in Puerto Rico, including Muñoz' Liberal Party, the senator opposed the measure. Muñoz Marin said that independence would hurt Puerto Rico's economy. (He contrasted the proposed bill with the provisions of the Tydings–McDuffie Act, which provided independence after a 10-year transition period.) Due to his opposition, the bill did not progress in Congress, and Puerto Rico did not receive its political independence from the U.S.

In 1950, the United States passed legislation to make the island an Estado Libre Asociado (a "Freely Associated State", more commonly called a "commonwealth"), a hybrid political status. Muñoz Marín, as Governor of Puerto Rico, supported the measure. Muñoz Marín became the first native-born elected governor of Puerto Rico.

After Riggs' assassination, many Nationalist Party leaders were imprisoned. Members of the Puerto Rican independence movement came under greater scrutiny and persecution. Among the leaders arrested were Pedro Albizu Campos, Juan Antonio Corretjer, Luis F. Velazquez, Clemente Soto Velez, Erasmo Velazquez, Julio H. Velazquez, Juan Gallardo Santiago, Juan Juarbe Juarbe, and Pablo Rosado Ortiz. The Nationalist Rafael Ortiz Pacheco, fled to the Dominican Republic.

These leaders were charged with having "conspired to overthrow" the U.S. government on the island. They were tried in Boston, Massachusetts, as that federal district court had jurisdiction for Puerto Rico. The first trial jury refused to convict, and ended in a hung jury. A second jury was picked, consisting solely of "Anglo-Americans." This jury found every Nationalist charged to be "guilty", with the exception of Juarbe Juarbe.