Buzz
At just after 3 a.m. on July 26, 1978, a humid summer night in Washington, D.C., John McCormick returned home after a long night shift. As the 63-year-old taxi driver approached his front porch, a man wearing a stocking mask emerged from the shadows, aiming a gun at him. Inside, McCormick’s wife Belva heard loud shouts followed by a gunshot. She quickly contacted the police, who arrived to find McCormick dead from a single bullet wound. The gunman had already disappeared.
Authorities discovered the stocking mask lying a few feet from the house. This was the second shooting in the area within a month, but it remained unclear whether the two incidents were connected.
Later, a confidential informant told authorities that a 17-year-old local named Santae Tribble might have owned a .32-caliber gun, similar to the one thought to have been used (although the actual weapon was never found). Yet, the only physical evidence linked to the crime was the stocking mask—and the 13 hairs that were still attached to it.
At the time, microscopic analysis was considered the most reliable method for examining hair evidence, and it played a central role in the physical evidence presented during Tribble’s trial. An FBI expert testified that one of the hairs found matched Tribble’s ‘in all microscopic features.’ In their closing argument, the prosecution assured the jury that there was ‘one chance in 10 million’ that the hair could belong to anyone else. Tribble was convicted in 1980 and sentenced to 20 years to life in prison.
Santae Tribble maintained his innocence, and in 2012, mitochondrial DNA testing on the hairs confirmed that none of them were his. Instead, the hairs belonged to three unrelated individuals and a dog. After more than two decades behind bars for a crime he didn’t commit, Tribble was fully exonerated.
Following Tribble’s case, the FBI discontinued its hair analysis program and launched a review of previous cases. Yet, despite the flaws in the method, many people still believe that microscopic hair analysis is nearly infallible, a perception largely fueled by historical cases and crime dramas on television.
The Problem with Microscopic Hair Analysis
Hair has long been used as forensic evidence, with its history tracing back to a murder trial in 1855 [PDF]. The case highlighted the potential of hair analysis, prompting European police to enlist medical pathologists to examine hair samples using microscopes. However, with limited experience and even more limited magnification capabilities, drawing reliable conclusions was often challenging. The microscopes of the time were much less advanced than today’s, with lower magnification and basic lighting systems, and pathologists were trained to identify signs of disease rather than the distinct characteristics of criminal suspects.
As forensic science progressed, hair analysis evolved into its own distinct field. It eventually became a regular feature on TV shows like Law & Order and CSI: Crime Scene Investigation— fueling widespread misconceptions about the capabilities of hair analysis in real-life investigations.
‘People watch a TV show and see someone take a hair from a crime scene, place it in a flatbed scanner, and suddenly, faces appear on the screen,’ says Jason Beckert, a microscopist at Microtrace, a materials analysis lab in Elgin, Illinois. In contrast, his actual work is much more involved and often works in tandem with other types of physical evidence analysis.
Microscopic analysis and DNA testing are often confused, yet they offer different insights for investigators. Beckert’s microscopic analysis is primarily used to provide visual comparisons and contextual clues during investigations. DNA testing, however, quantifies genetic information from cells. Hair itself doesn't contain DNA for forensic use unless it has cells at the root, which are necessary to generate a viable DNA profile. For identifying individuals with certainty, DNA testing is essential.
Hair is one of the most frequently found physical evidence types at crime scenes, as an average person sheds anywhere from 50 to 100 hairs daily. Technicians gather as much hair as possible from the scene, and then the samples are analyzed using specialized microscopes. Skip Palenik, a microscopist who specializes in hair and fiber evidence at Microtrace, explains that today's techniques are far more advanced than those used with historical microscopes.
Modern specialized microscopes feature an optical bridge that allows examiners to compare samples from a crime scene directly with those from a suspect. Using these powerful tools, trained specialists can observe intricate details within the protein layers of human hair, such as its shape, color, density, and texture. They also identify patterns and damage, like hair being pulled, ripped, or burned, or naturally shedding. Additional clues, like cosmetic treatments or even louse eggs, can offer insights into the hair’s history.
‘An expert can draw certain conclusions,’ Palenik says. ‘What microscopy can tell you is that two hairs are indistinguishable from one another. But that’s different from saying they come from the same person.’
DNA: The Definitive Method
During Tribble’s trial, the prosecution presented a statistical probability of one in 10 million that the hairs found on the stocking mask belonged to him. However, there are no statistics that explain how many people share the same hair color, texture, or type. A variety of genes influence these traits, and hair characteristics can even differ from person to person in the same family or from one part of the head to another. Furthermore, some features examined under a microscope may change throughout a person’s life, due to both personal choices and natural biological changes.
In contrast, DNA profiles are unique to each person, remain constant throughout their life, and can be compared with population databases. DNA profiles don’t fluctuate based on the analyst and are rooted in statistics, not subjective visual inspection.
Repeatedly, DNA analysis has proven that hairs identified through microscopy as belonging to a specific individual actually could not have come from that person. Without population-based statistics, relying on the visual traits of hair to definitively identify someone is fundamentally flawed.
For many, including Santae Tribble, the truth came far too late. After his exoneration, he became an advocate for others wrongfully imprisoned, speaking out about his experience and urging law enforcement and prosecutors to reassess how microscopic hair analysis was used in courtrooms. He passed away in June 2020 after battling a prolonged illness.
The murder of John McCormick remains officially unresolved.
