About

I am the Gerhard Casper Postdoctoral Fellow in Rule of Law at the Center on Democracy, Development and the Rule of Law (CDDRL) at the Freeman Spogli Institute for International Studies (FSI) at Stanford University. I study criminal and political violence, with a geographic focus on Latin America. I am particularly interested in understanding armed actors, including police and armed groups, their attitudes and behaviors. My book project investigates why police form armed groups. I received my Ph.D. in Government at Georgetown University in the Comparative Government subfield in 2025. My work has received support from Georgetown University, Fundação Estudar, the InterAmerican Development Bank, UNU-Wider, the Harry Frank Guggenheim Foundation’s Emerging Scholars initiative, and others. I will join the School of Government at the Pontifical Catholic University of Chile, in Santiago, as an Assistant Professor in July 2026.

Research

Book Project: Forming from Within: Police-Led Armed Illicit Groups (in progress)

In Forming from Within, I introduce the concept of police-led armed illicit groups (PLAIGs) and explain why and under what conditions police officers form them. I conduct case studies of Rio de Janeiro and São Paulo from the 1980s to the 2000s, and use Bayesian qualitative reasoning and process tracing to evaluate evidence from criminal records, primary and secondary sources, and interviews. I argue that the rise of armed threats raised the perceived costs of policing, leading some officers to offset costs by forming PLAIGs to make extra income. Officers were able to do so in Rio because of the police’s competitive coercive capacity and low level of control. Conditions in São Paulo, where PLAIGs did not form, were the opposite. Challenging the conventional view that armed groups form only where the state is absent or weak, Forming from Within repositions police as a central object of analysis in studies of state development and demonstrates that investments in state capacity can fragment, rather than consolidate, the monopoly over the use of force.

Peer-Reviewed Publications

Bullock, J. Pellegrino, A. P., 2022. How do Covid-19 stay-at-home restrictions affect crime? Evidence from Rio de Janeiro, Brazil. EconomiA, v.22 n.3. [op-ed]

Working Papers

Wars and Words

(with Benjamin Burnley and Laia Balcells) Does the outbreak of a major international war change political discourse? Drawing on theories of political communication and elite cueing, identity salience, and threat perception, we hypothesize that the outbreak of a war of aggression by a major power increases the use of nationalist rhetoric by heads of government in other, non-belligerent, states. To test this hypothesis, we analyse over 10,000 tweets by heads of government from 130 countries before and after the Russian invasion of Ukraine in February 2022. Using word embeddings, we map politicians’ tweets along a nationalist–cosmopolitan spectrum and show a significant shift toward nationalist political discourse on the online platform. Subgroup analysis reveals that this effect was stronger among leaders of member states of the North Atlantic Treaty Organization (NATO). Yet, leaders from countries that are members of the pro-Russia Collective Security Treaty Organization (CSTO) and those with past experiences of irredentism or territorial armed conflicts—thus resembling the Russia–Ukraine war—did not increase their resort to nationalist rhetoric. These findings offer new insights into how—in the digital age—conflict in one place can diffuse into politics elsewhere. UNU-Wider Working Paper

Killings of police officers

What happens when a police officer is killed? In this project, I analyze how police officers’ deaths in Rio de Janeiro impact police use of lethal violence in the following days. I find that police have become more deadly, albeit not more active. Such an effect is shaped by police officer schedules and local remembrance practices. [Working paper upon request] - Presented at APSA 2023 and ISA 2024

International Wars, National Foes

(with Laia Balcells and Matthew Simonson) Can international armed conflicts exacerbate existing tensions in other regions? How do countries with a history of violence respond to armed conflicts in distant parts of the world? International wars that imply changes in international norms could increase the fear of internal conflict recurrence. We examine these questions with a survey experiment conducted in Bosnia & Herzegovina and Serbia, where respondents were exposed to news headlines about either a) the ongoing Russia-Ukraine War, b) the ongoing Israel-Gaza War, or c) a placebo. While the treatments affected respondents’ emotions, contrary to our pre-registered hypotheses, we find that exposure to news of these conflicts does not alter respondents’ expectations of future violence, nor does it significantly impact the salience of their various identities. Additionally, attitudes toward neighboring ethnic groups and policy preferences, as well as expectations of future violence, remained largely unchanged by either treatment. [Pre-analysis Plan] Presented at APSA 2024 (R&R)

Armed Groups and Public Support for Peace

(with Lesley-Ann Daniels and Laia Balcells) What makes the public see armed groups as acceptable partners for peace instead of targets of law enforcement or military action? We examine legitimacy as an important but underexplored factor in determining when the public accepts peace negotiations with an armed group and on what settlement terms. We unpack legitimacy into motivational, material, and moral dimensions, which shape public perceptions through compliance with the social contract, institutional recognition, and ethical appraisal. A group’s legitimacy is informed by different characteristics and behaviors. We test this argument in a conjoint experiment embedded in a unique online survey of 2,100 respondents in Colombia. The findings will help inform public attitudes to negotiations with armed actors, which can help create a more accepted peace. [Pre-analysis Plan]. Presented at ISA 2024

Teaching

Georgetown University, Teaching Assistant

GOVT 040 - Comparative Political Systems / Introductory comparative politics undergraduate seminar, Professor Langenbacher, Fall 2020;
GOVT 702 - Quantitative Methods II / Ph.D method sequence, Professor M Bailey, Spring 2021 & Spring 2022.

Pontifical Catholic University of Rio de Janeiro, Minicourse Instructor

Quantitative Methods for the Social Sciences, Spring 2024.
Civil Society Diplomacy. Fall, 2017 and Spring, 2018. Best-evaluated minicourse in 2017.

Pontifical Catholic University of Rio de Janeiro, Teaching Assistant

Theoretical Foundations of International Relations II / Professor C F P D S Gama. Fall, 2013
Violence and International Relations / Professor M Herz. Spring, 2014.

CV

Please find my CV here.

Contact

You may reach me at pellegrino@stanford.edu.