[1] According to video evidence and a joint church-labor investigative commission, UMOPAR opened fired on unarmed protesters, at least two of whom were fatally shot, and many of whom fled to their deaths over a steep drop into the San Mateo River.

[2][3][4] The killings were followed by further state violence in Villa Tunari, Sinahota, Ivirgarzama, and elsewhere in the region, including machine gun fire, beatings, and arrests.

[1] Representatives of the National Congress, Catholic Church, Permanent Assembly for Human Rights, and the Central Obrera Boliviana labor federation formed a joint "multisectoral commission" to investigate the repression in the Chapare, which traveled to the region on 30 June 1988.

They received tactical and technical support from the US Drug Enforcement Administration (DEA) who maintained an operational base in the Chapare region of the country[7][8] as did the Bolivian coca eradication and substitution agency Direccion de Reconversion Agricola (DIRECO).

[10] In 1988, the DEA and UMOPAR began the antinarcotics Operation Snowcap, while US Border Patrol agents supported Bolivia police checkpoints on roads in the Chapare.

[13] Bolivian coca growers in the region alleged that in addition to providing logistical assistance to UMOPAR the DEA was also responsible for this chemical eradication of their crops.

On 11 June, farmers in Villa Tunari threatened to take over coca-eradication facilities by force if the Bolivian congress approved the Ley 1008 legislation that would classify coca-growers as cocaine traffickers.

On 15 June, meetings between growers and the government ended without reaching any resolution on these issues and DIRECO officials soon went on collective vacation, aware of the farmers’ intentions to take direct action.

[15] Following a night of meetings in Villa Tunari,[16] peasant leaders made the decision to visit the DIRECO facility that was adjacent to the UMOPAR barracks in order to address directly the agency’s use of herbicides.

[25] Despite a multisectoral research commission’s findings that the gathered peasants had up until this point shown neither violence or aggression,[24] an UMOPAR soldier radioed for reinforcements from the nearby town of Chimoré.

[22] Upon arrival to Villa Tunari at 10:30 am, the reinforcement UMOPAR forces under the command of Major Primo Peña acted in what has been described as "disproportionate" and "brutal" violence.

[24] Eyewitnesses claimed that as many as twenty peasants attempting to escape the crossfire by fleeing from the back of the camp fell 30 meters into the San Mateo River and drowned.

Journalist Jo Ann Kawell summarized the "hour-long video tape made by a crew from a local television station": Hundreds of marchers, dressed in shabby work clothes and carrying no visible arms, not even sticks, approach the post.

[28] Information Minister Herman Antelo publicly alleged that the peasant protesters were armed with carbines, revolvers, and dynamite cartridges, obligating the police to act in defense of the law and themselves.

[28] The multisectoral commission concluded that "not only does not a single piece of evidence prove this, but also the testimony of persons of religious [observers] is unanimous in signally that they did not see anyone either drunk or armed.

"[33] Jo Ann Kawell, describing video evidence of the massacre wrote, "The farmers later charged that agents of the U.S. Drug Enforcement Administration had encouraged the police action.

Residents Danitza Guzmán de Gordillo, Francisco Choque Sausiri and others were arrested and several union and civic leaders kidnapped in what the Multisectoral Commission later described as a climate of "fear, anxiety and intimidation".

[38] Municipal council leader José Villarroel Vargas attributed the repression to "North American military troops who entered" Villa Tunari on the day of the massacre.

[16] Soon afterwards, Morales was elected to head the Federation of Peasant Workers of the Tropic of Cochabamba as part of a slate known as the Broad Front of Anti-Imperialist Masses (Frente Amplio de Masas Anti-Imperialistas).