• Spatial and Social Context of Crime and Deviancy

  • Crime Concern and Crime Responses 

Computer Programming

Computational Methods

  • Supervised and Unsupervised Machine-learning Techniques 

  • Network Analyses  

Neon Painted Face


  • Repeat Victimization, Polyvictimization 

  • Risk Factors and Instrument Development

Featured Publications 

Understanding factors associated with re-referral of youth for commercial sexual exploitation

Since the passage of the Victims of Trafficking and Violence Prevention Act of 2000 in the United States, awareness has increased about the problem of commercial sexual exploitation of children (CSEC). Moreover, United States Federal law calls upon child welfare agencies to establish policies and practices that help identify and provide services to minors at risk of CSEC. Although awareness has increased about the problem of CSEC, little attention has been paid to understanding why some youths are re-referred to CSEC programs after initial referral and intervention.The present study examines which factors drive re-referrals of youths for CSEC concerns. Data about a population of high-risk youths (n = 416) referred to a CSEC-specific program in the Northeast of the United States between 2011 and 2018. Using logistic regression analyses, we investigate what factors are associated with youth having multiple referrals.Youths with multiple referrals were more likely to have histories of missing from care (OR = 2.996, p < 0.001), substance misuse (OR = 2.802, p < 0.01), and greater agency involvement (OR = 1.260, p < 0.05). However, youths with multiple referrals were not at heightened risk of CSEC as compared to youths that were not re-referred. The results demonstrate that re-referred youths meet the profile of a victim as depicted on screening and assessment instruments, which has important implications for victim services and referral systems dedicated to identifying CSEC and protecting youths who may experience re-victimization for CSEC.

Kafafian, Matthew, Ieke de Vries, Amy Farrell, Elizabeth Bouchard, Susan Goldfarb. 2021. Understanding factors associated with re-referral of youth for commercial sexual exploitation. Child Abuse & Neglect 117. [article link]

What determines immediate risk to commercial sexual exploitation among a population of high risk youths?

Examining risk to commercial sexual exploitation of children (CSEC) is challenging. Youth often do not self-identify as victims of CSEC, but may disclose other experiences that signal their increased risk to CSEC. Prior studies have begun to examine the importance of the disclosure of experiences such as a history of abuse, running away, or substance abuse. While these are experiences that help identify risk within a general population of youths, less is known about what ultimately puts high-risk youths at immediate risk to CSEC. High-risk youths have experienced a multitude of different childhood adversities, but determining which of these childhood adversities signal immediate risk to CSEC has proven to be methodologically challenging. This study uses a machine-learning method to identify the most decisive risk items for CSEC among a sample of 317 high-risk youths who were referred to a CSEC-specialized program in the Northeast of the U.S. The findings demonstrate that a select set of seven items were the most important experiences that signaled immediate risk to CSEC: (1) being approached to engage in CSEC; (2) sexual assault; (3) engaging with people known to be involved in CSEC; (4) being seen in areas known for CSEC; (5) having multiple sex partners; (6) traveling out of state; and (7) being threatened in any other way than with physical or sexual assault. These findings have important implications for screening and assessment instruments.

De Vries, Ieke, Matthew Kafafian*, Kelly Goggin*, Elizabeth Bouchard, Susan Goldfarb, and Amy Farrell. 2020. Enhancing the Identification of Commercial Sexual Exploitation among a Population of High-Risk Youths Using Predictive Regularization Models. Child Maltreatment 25(3): 318-327[article link]

Does concern about human trafficking and willingness to engage in crime responses differ by men and women? 

While human trafficking has received much concern among a general public, this concern is gendered. Using data from a national probability sample of approximately 2,000 Americans, this study shows that women are more likely to be alarmed about human trafficking when they believe both transnational crime and gender discrimination are at the roots of the problem. Men are concerned about human trafficking when they perceive gender discrimination alone to be the underlying problem. While these crime concerns are driven by distinct problem frames, public alarm about human trafficking - once reached - activates engagement in crime-solving efforts among both men and women. Understanding gender differences in public alarm and responses to crime is of utmost importance to close the gender gap in crime responses, and may ultimately help enhance the detection of the crime. 


De Vries, Ieke, Amy Farrell, Vanessa Bouché, and Dana Wittmer. 2020. Crime Frames and gender differences in the activation of crime concern and crime responses. Journal of Criminal Justice 66[article link]

What are the challenges for police to respond to victims' needs?  

Police are often the first responders to crime victims, yet research on examining police effectiveness has been less attentive to the needs of victims. This study examines perspectives on how police respond to trafficked persons who typically do not self-identify as victims. A review of human trafficking investigations and in-depth interviews with police and service providers in three U.S. communities illuminate several challenges in the current response model, which relate to barriers in identification, lack of trust between victims and police, and recognition of victimizations.  With an increasing awareness on human trafficking, police are increasingly called upon to respond to this crime type. The findings of the current study help guide a victim-centered approach in policing that improve police interactions with victims, affirms victimization experiences, and guarantees safety from further harm. 


Farrell, Amy; Meredith Dank, Ieke de Vries, Matthew Kafafian, Andrea Hughes, and Sarah Lockwood. 2019. Failing Victims? Challenges of the police response to human trafficking. Criminology & Public Policy 18(30): 649-673[article link]