Latin American countries are losing control of their police forces due to growing economic inequality, leading to political violence aimed at the poor, warned John M. Sheffield II ’09, during a presentation on police brutality in South America yesterday evening.

The discussion focused on the two summers Sheffield spent in Buenos Aires, working with the Argentinean human rights group La Liga Argentina por los Derechos del Hombre, as well as researching his thesis there.

Sheffield, who is an undergraduate associate and research fellow at Harvard’s Weatherhead Center for International Affairs, emphasized how “political polarization” between the rich and the poor in Buenos Aires also facilitated police repression of the city’s underprivileged.

“The state will not prosecute a police who shoots a poor person in the line of duty,” he said.

Sheffield first encountered police violence in Argentina when he was there with Harvard’s David Rockefeller Center for Latin American Studies internship program and La Liga had him working on a court case involving police brutality.

During his second summer in the country, Sheffield experienced institutionalized violence firsthand, when he was beaten by members of the Buenos Aires police force.

Having conducted interviews with around 50 junior police officers in Argentina, the Pforzheimer resident and social studies concentrator concluded that an increasing “gap between cops on the street and cops in the office” has put police in states such as Argentina and Brazil out of the reach of governmental control.

Although he criticized the systematic violence occurring underthe direction of upper-level police officials, Sheffield acknowledged that most police violence resulted from misconduct by individual officers.

Sheffield ended his presentation by encouraging Harvard students to join Proyecto Espartaco, a “wiki for human rights” he has been working on to help Latin American human rights groups share information. He said his hope is to harness the tremendous resources of American students for the benefit of the movement.

The event’s participants—many of whom were Cambridge residents not affiliated with Harvard—expressed positive reactions to the presentation. Panagiotis Angelopoulos ’12, who came to the talk because of his own interest in Latin American human rights, said he appreciated the speaker’s unique perspective.

Rebecca E. Taylor, a community member and recent college graduate, praised Sheffield’s “adept use of academic phrases” while remaining “accessible.”

The presentation was the first in a monthly series entitled “Student Stories from Latin America,” hosted by the Harvard College Human Rights Advocates.