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AAAS Fellow, Statistician Alicia Carriquiry Explains the Perils of Faulty Forensic Science Analysis

There’s way more to analyzing fingerprints, handwriting samples and other pattern forensic evidence than you might think, says Alicia Carriquiry, director of the Center for Statistics and Applications in Forensic Evidence (CSAFE) at Iowa State University.

AAAS Fellow, Statistician Alicia Carriquiry
AAAS Fellow Alicia Carriquiry.

The AAAS Fellow says it’s not enough for a forensics expert to testify in court that microscopic pieces of glass found in a suspect’s hood are the same glass from a crime scene’s broken window, for example. What experts should realize is the glass could have come from a construction site that’s using the same kind of glass as the broken window.

Carriquiry contends forensics experts should go beyond obvious conclusions and ask themselves whether there’s any other possible explanation for a situation involving what is known as “pattern evidence,” particularly because an incomplete analysis could lead to wrongful convictions.

“The jury is only provided with one side of the story,” Carriquiry says. “If you’re a juror, you would say, ‘Oh, the fragments must have come from the broken windows at the crime scene,’ but they could have come from anyplace else.”

Carriquiry, a distinguished professor of statistics at Iowa State University studies how pattern forensic evidence is used in criminal cases and develops statistical methods that answer questions about it. Think of pattern forensic evidence as the type of evidence that is left from physical contact or actions, such as shoe prints, tire treads, gun ballistics, blood stains and handprints. It can be observed digitally and at the crime scene itself by investigators.

“So, these are pretty old disciplines and the thing is they rely on subjective assessments,” she says. “This is subjective in the sense that you know not every examiner will identify the same minutiae and they measure nothing….and they say, ‘Yes this looks like a match or it doesn’t look like a match or this is inconclusive.’”

Experts should, for example, not only make sure the suspect’s shoe is the one that left the print at the crime scene, but also identify the make and model of the shoe that generated the print.

Her center carries on several projects in this space. It carries out research and conducts studies to connect data. In the glass example, the center would examine how similar glass is from batch to batch by visiting a glass factory every day for a month, comparing the glass produced there, then recording the variability in the manufactured glass. It then releases big data sets it puts out into the public domain to help others with their research. Related work includes developing statistical methods, using samples or images for machine learning algorithm development and statistics.

The center also offers training through workshops and distance classes to improve quantitative literacy for legal and forensic professionals. There, they learn basic questions to ask about evidence and things they should be looking for.

Finally, the center conducts engagement and outreach to forensic scientists. Most of the people working with Carriquiry at the center aren’t forensics experts — they’re statisticians, mathematicians, computer scientists, lawyers, criminologists and psychologists — so they need to engage across fields.

Forensic science and its implementation have real-world consequences. People’s lives and their freedom often depend on forensic analysis, which is why it’s important for Carriquiry and her colleagues to get it right.

“The number of people that have been locked up for decades for crimes they didn’t commit is staggering,” Carriquiry says. 

Following two high-profile incidents involving the FBI (the 2004 Madrid train bombings and a review of FBI state and federal cases that used microscopic hair analysis in 2015), as well as a 2009 report from the National Research Council, which was critical of how forensic science was done in the United States, Carriquiry decided to get to work. Her focus was on raising awareness about the need to improve forensic practice in the United States at the national level. Using her expertise in statistics, she knew she could help search for better solutions. As a result of her initial efforts, she was able to secure funding for CSAFE in 2014 which enabled her to open it in the following year.

Since its opening, CSAFE research has brought together forensic practitioners and other stakeholders through education and training opportunities. It has also helped the Innocence Project in cases where faulty forensic evidence led to a wrongful conviction. Rewarding its success, CSAFE’s primary funder, the National Institute of Standards and Technology, promised $20 million in new funding to the effort over the next 5 years earlier this year.

Carriquiry says being named a AAAS Fellow helped her on this journey by providing ways for her to interact with scientists from so many different disciplines. It’s a seal of approval that the Uruguay native says makes her a more credible scientist.

Forensic science, meanwhile, is an area she says has been very insular in the sense that it hasn’t had much input from the broader scientific community, maybe because these techniques were developed in crime labs or pioneered by police.

She encourages her fellow scientists to look into it, and she’d love to talk to anyone about getting started in this field. There’s a whole lot of work to do in this area and there’s room for scientists of all stripes, she says. But scientists should know there’s a lack of data in the public domain and that funding for it isn’t terribly abundant.

“When you think about forensic science funding and agriculture and medical funding, it’s like a minute fraction,” she says. “But the problems are important, the impact of forensic science on society and the fairness of the criminal justice system is tremendous and the questions that need answers are fascinating from a scientific point of view.”


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