Crime dramas like “CSI” are wildly popular—but the real stories of forensic science in the courtroom put our own beliefs on trial.

Forensic techniques and analyses, from hair to handwriting to DNA, have brought cutting-edge science into the American courtroom for over 150 years. But the history of forensic science isn’t just about technologies that can use traces of evidence like a fingerprint or a drop of blood to link a criminal to a crime.

The story of forensic science is also about the people who designed and created methods to uncover such scant evidence and turn it into convictions. And when evidence is in hand, the different ways that humans examine and judge forensic data are influenced both by their personal thoughts and by how other forensic cases have played out in the past.

These themes are explored in a new exhibition at the Smithsonian’s National Museum of American History, “Forensic Science on Trial.” Opening Friday and running through next summer, the exhibition gathers artifacts from the museum’s extensive science collections, as well as special loans.

“You really get to see what the human hand is, in both making and understanding forensic science,” says exhibition curator Kristen Frederick-Frost.

Historically, many sexual assault cases have been a matter of one person’s word against another, with convictions hard to come by. In the 1970s, women’s rights advocate Martha “Marty” Goddard set out to change that. She pioneered a standardized system to increase the chances that perpetrators of rape and sexual assault would be caught and prosecuted. Goddard interviewed law enforcement, lawyers, hospital workers and others to learn how best to collect evidence of sexual assaults. On display is the kit she designed, the Vitullo Evidence Collection Kit for Sexual Assault Examination, which contains tools necessary to collect that critical evidence, such as a stylus for scraping under fingernails, combs, glass slides, swabs, evidence bags and instructions on how to best preserve the evidence for use in court.

“The kit was created when trace evidence was core in investigation and prosecution, before DNA was used,” explains Katherine Ott, a curator of medicine and science at the museum, alongside Frederick-Frost. “It was also a time when sexual assault was misunderstood, seldom reported and generally not taken seriously. Detectives, attorneys, and the nurses and doctors who dealt with it were not really talking with each other.”

DNA evidence is often key to such cases today, but it’s not infallible; DNA degrades and isn’t always present. “Other kinds of evidence, like fingerprints and shoe prints and the materials collected in Marty’s early version of the kit, are often key to solving the ‘he said, she said,’ problem,” Ott says.

While the sexual assault kit was an individual effort, the Central Records System Filing Cabinet and Index Cards, created around 1950 and on loan from the FBI, shows a large-scale initiative from the federal government to make a different kind of crime-fighting system. This widespread attempt to collect and organize fingerprint and other data in a central repository was used to try to match criminals to the trace evidence they left at crime sites.

“We pair these objects together because one of them is a grassroots effort to organize, and provide a solution for identification, while the other is a top-down effort,” says Frederick-Frost. “But in both cases, as always, you have to have buy-in to get people to think about what would be convincing evidence at any point in time.”

Though forensic evidence might seem like a matter of scientific facts rather than opinion, the way data is gathered, and the way it’s ultimately judged, has always been influenced by people’s personal beliefs. A 1921 polygraph on display was one of the first to be used to test for deception, created by a police officer and physiologist named John A. Larson. Larson’s device was designed to detect physiological responses to questioning, such as heart and breathing rate and blood pressure, that would indicate a suspect was lying.

A polygraph lie detector designed in 1921 National Museum of American History

But, because people react to interrogations differently, no one pattern of responses can actually indicate when someone is lying. Some people may be nervous even when being truthful, while practiced liars may not be particularly anxious while doing so. “With that polygraph, it kind of works best if you believe it works” Frederick-Frost says. “That’s fascinating to me, that your beliefs can impact what kind of data is produced.”

Human beliefs also took center stage in The People of the State of California v. Orenthal James Simpson (1994-1995). Investigators used DNA autoradiograph analysis to match blood from the crime scene to the defendant, O.J. Simpson, as well as bloodstains found on a sock in Simpson’s home to the murdered Nicole Brown Simpson. In the Simpson case, human judgments weren’t focused so much on how data was analyzed. Instead, they centered on confidence in the people and processes that provided that data to the lab. “Whether people believed the LAPD did or did not tamper with the evidence impacted how that data was received,” says Frederick-Frost.

While the history of forensics is one of advancing science, in which the latest and greatest technologies take center stage, the past often shapes how data is collected and presented for trial. During the 1860s and ’70s, all three of Lydia Sherman’s husbands and eight children—six of her own—died under suspicious circumstances. After an autopsy revealed that her last husband had been poisoned, Sherman was convicted of murder and sentenced to life in prison, largely on the strength of chemical analysis performed by George Frederick Barker.

Curiously, Barker subjected the organs of Sherman’s victims, some exhumed from the grave, to many different types of arsenic tests when one would have sufficed to identify the poison. Why? During the previous year a wealthy Baltimore widow named Elizabeth Wharton was accused of murdering General W. Scott Ketchum by poison but found not guilty. “She was able to bring in top medical experts to attack the evidence, and she did so successfully, and one of their lines of attack was that the antimony tests used for that trial were outdated,” Frederick-Frost notes. “Barker threw everything and the kitchen sink at the Sherman evidence,” she adds, “and he admitted later that he did that because of what had happened the year before.” The tests that helped convict Sherman are a focal point of the exhibition.

Few objects of forensic evidence are steeped in as much history as the pistol confiscated from Nicola Sacco, and a bullet that was recovered from the body of a victim who was allegedly killed by Sacco and Bartolomeo Vanzetti during an armed robbery in Braintree, Massachusetts, in 1920. The pair’s status as Italian immigrants and anarchists played a major role in their trial and subsequent appeals, which eventually ended with their execution and with widespread doubts concerning their guilt or innocence that linger to the present day.

Pistol confiscated from Nicola Sacco, May 5, 1920 National Museum of American History

“That particular bullet and that particular gun have been analyzed over and over and over again since 1921, using different techniques, with everyone thinking that the latest and greatest technique would be able to tell us definitely whether or not they did it,” Frederick-Frost says. Not one has been successful, and this contentious criminal case continues to inspire new ideas and theories.

“That case didn’t just occupy the imagination of the whole country, it was worldwide,” Frederick-Frost says.

Though few other cases have ever attained Sacco and Vanzetti stature, the exhibition notes other examples of the unique, enduring relationship between the media and forensic science. This includes the handwriting samples used to help convict Bruno Richard Hauptmann of kidnapping and killing the son of Charles Lindbergh, in a case that some dubbed a “crime of the century,” and a blood spatter head used in Showtime’s “Dexter.”

“Through the history of modern forensic science, dating from the 19th century, there has been kind of a back-and-forth trade-off between fiction and real life,” says Simon Cole, a criminologist at the University of California, Irvine, who specializes in the history and sociology of forensic science. “They are always kind of influencing each other.”

But unlike in fictional cases, which are often closed by forensic evidence without a shadow of a doubt, Cole warns that no matter how much technology advances, there is always a need for caution in real investigations. New techniques may be hailed as infallible, but time will show they have limitations. “To me the lesson is always, the next time someone tells you something is infallible, exercise some skepticism,” he says.

For Frederick-Frost, such limits on even the best techniques simply highlight the primacy of a human role in forensic science, from the development of forensic systems to the ultimate judgment of their value.

“In the end you always have to say either the data is good enough, or it isn’t good enough,” she says. “And that is a human judgment.”

“Forensic Science on Trial” is on view from June 28, 2024, through June 2025 at the National Museum of American History.

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