Insights & Expertise

When and How Evidence is Presented Impacts Suspect Cooperation, New Study Finds

Christopher E. Kelly, Ph.D., associate professor of criminal justice, is PI on a Department of Defense grant examining how and when evidence is presented during investigative interviews in the U.S. His research, conducted in collaboration with Saint Joseph’s students, will inform a new training program for federal law enforcement.

Closeup of police officer questioning a suspect at a table

by Diane Holliday

We’ve all seen the high-pressure interrogation scene play out on TV: A suspect is confronted by a less-than-friendly investigator with mounting evidence linking them to a crime — fingerprints, video surveillance, eyewitness testimony — ultimately leading to an admission of guilt.

While these interrogation techniques may be real, the resulting cooperation on behalf of the suspect is far less true to life. That’s according to an ongoing research study led by Christopher E. Kelly, Ph.D., associate professor in Saint Joseph’s University’s Department of Sociology and Criminal Justice. 

Kelly is the PI on a grant from the U.S. Department of Defense’s Irregular Warfare Technical Support Directorate (IWTSD) that examines how evidence is presented during investigative interviews in the U.S. His findings, and the model he’s developed to code and evaluate evidence presentation, will serve as the basis for a two-day training program this summer for federal law enforcement. 

His study analysis includes how and when to present evidence during interrogation and the effects evidence presentation has on building rapport, assessing credibility and gathering information from detainees.

Laying the Cards on the Table

As it turns out, introducing evidence at the beginning of an interrogation rarely leads to cooperation.

“In the first study we conducted, we actually saw the opposite,” says Kelly. “The resistance — denials, minimizations, deflections, claims of poor memory — increased during the presentation of evidence.”

Kelly conducted studies again and again, in different cities looking at different types of criminal acts, and the results were the same. Evidence increased resistance.

“I started thinking this was a unique finding to me based on the way I designed or led these studies,” he says. “Then I was invited to work with two different research teams, one in the U.K. looking at sex offenders and one in Sweden looking at serious violent crimes and, sure enough, same findings.”

What also emerged from these studies is how evidence presentation goes hand-in-hand with confrontation and an accusatorial approach. “The trick is to present evidence in as least a confrontational manner as possible, which is very challenging to do,” says Kelly.

The resistance — denials, minimizations, deflections, claims of poor memory — increased during the presentation of evidence.

Christopher E. Kelly, Ph.D.

Associate Professor, Department of Sociology and Criminal Justice. 

Confrontation is one of six interrogation methods defined by Kelly in a previous study. Other techniques include context manipulation (interrogating the detainee in a small room or isolating them) and rapport-building (building a bond with the detainee and meeting their basic needs).

“You get more flies with honey,” says Kelly. “Don't use evidence to overcome resistance, use it to assess credibility — in other words, lie detection — and then gather more information. Because once you challenge somebody that you've caught in a lie, it's an opportunity to get more information.”

Mentoring Future Researchers 

Kelly has worked on multiple iterations of this research over the years, always bringing Saint Joseph’s students into the fold through the Summer Scholars program, classroom learning and other research opportunities. 

For this particular grant, he’s working with two criminal justice majors, Lesley Reyes Pina ’22 and Deanna Smith ’21, who are helping to code the interviews, looking at what the interviewer is doing and saying and what the interviewee does in response.

"Working on Dr. Kelly's project has made me realize how important it is to reevaluate the way our system works in dealing with interrogation methods," says Reyes Pina. "I think it is really important to see how science-based research can strengthen interrogation approaches throughout federal, state and local law enforcement.”

Recent alumna Margarita Parker ’20 was also onboarded as Kelly’s research assistant.

“Margarita was a student in my Introduction to Criminal Justice class in 2017. There was something about the way she processed information that I have never encountered before,” says Kelly. “She understood research in such a raw way and actually picked out a couple of inconsistencies in findings of published work. It was amazing.”

What’s more amazing is Parker’s senior thesis, examining different types of evidence — whether it be physical, circumstantial or even bluffed — and its effects on interrogations actually inspired this project. Her thesis is cited in Kelly’s grant application.

“Even though I've been working with Dr. Kelly on investigative interviewing for nearly six years, I still am surprised when I see my senior thesis cited in our literature review and matrix. I am proud of how far this research has gone,” says Parker, crediting Kelly for developing the project and shedding light on investigative interviewing.

This summer, the group’s research will be translated into a series of training programs for federal law enforcement before being turned over to the government. Working with the students, Kelly says, has been highly rewarding.

“I love working with students on projects like this. To learn how to do research is a hard skill, a marketable skill. Students come out of their undergraduate experience and get a job doing research full time," he says, "I’ve hired undergraduates and numerous students after they’ve graduated and they always impress me.”