The Uncertain Future of Forensic DNA Phenotyping

From "The X-Files" to the Forefront of Forensics

Inspired by Dana Scully's scientific approach to crime-solving in "The X-Files," Dr. Susan Walsh embarked on a career in forensic biochemistry. Intrigued by the possibility of using DNA to predict physical appearance, she began researching forensic DNA phenotyping (FDP) in 2005. Now an assistant professor at Indiana University Indianapolis, Walsh is a leading expert in the field, developing tools to predict traits like eye, hair, and skin color from DNA samples.

The Allure and Limitations of Facial Prediction

While FDP can provide valuable leads in criminal investigations by predicting certain physical traits, Walsh remains cautious about its application to facial morphology – predicting facial structure from DNA. She emphasizes that the science isn't advanced enough for reliable facial prediction, acknowledging the complex interplay of genetics and environmental factors in shaping a person's face. "We can't even do a nose right now," she quips.

Parabon NanoLabs: A Controversial Player

Parabon NanoLabs, a private company, has emerged as a major provider of FDP services to law enforcement. However, their Snapshot system, which claims to predict face shape along with other physical traits, has drawn significant criticism from the scientific community. The company's proprietary methods lack independent verification and peer review, raising concerns about their scientific validity and potential for misuse.

"Selling these singular images to police is detrimental to the field and something we need to stop," Walsh argues, highlighting the risks of relying on unproven tools in a criminal justice system already fraught with bias.

The Science Behind the Snapshot

Parabon's Snapshot system uses a statistical method called principal component analysis and a dataset of around 1,000 volunteers to generate its predictions. However, critics like Mark Shriver, a Penn State geneticist who initially collaborated with Parabon, argue that the dataset is too small and diverse to support individual facial predictions. "Garbage in, garbage out," Shriver warns, emphasizing the importance of robust data for accurate analysis.

The Edmonton Case: Racial Profiling and Misinformation

The Edmonton Police Service's use of Parabon's Snapshot in a 2019 rape case sparked public outrage. The generic image of a Black man released by the police was seen as promoting racial profiling and over-surveillance of minority communities. The incident highlighted the potential for FDP to exacerbate existing biases within the criminal justice system.

"It's not a real image of a person... and it can only harm both the investigation and communities of color," Jennifer Lynch of the Electronic Frontier Foundation emphasizes.

The Chanel Lewis Case: Fourth Amendment Implications

The Chanel Lewis case, involving the 2016 murder of Karina Vetrano, raises serious questions about the use of FDP and its impact on Fourth Amendment rights. The NYPD's undisclosed use of Parabon's services to identify Lewis as a suspect highlights the lack of transparency surrounding investigative leads generated by such tools.

The Need for Verification and Validation

Experts like Jeanna Matthews, a computer science professor, stress the urgent need for independent verification and validation of forensic software like Parabon's Snapshot. The lack of rigorous testing and peer review raises serious concerns about the reliability and fairness of these tools when life and liberty are at stake.

"The idea that anyone is hiding behind trade secrets when life and liberty is at stake, we have to ask ourselves some serious questions," notes Rebecca Wexler, a law professor at UC Berkeley.

Protecting the Integrity of Forensic Science

For Dr. Walsh, the ongoing debate surrounding FDP underscores the importance of scientific rigor and transparency. She remains committed to developing and using FDP responsibly, prioritizing robust data, open communication, and ethical application to ensure its positive contribution to forensic science.

“How can I protect people more? How can I make sure that there is no way this can be used badly?” she asks.