A hair sample recovered from the home of kidnapped 84-year-old Nancy Guthrie failed to produce a DNA profile of any suspect — six months into an investigation that has burned through multiple FBI labs and over $1.2 million in reward money with no arrests.

For decades, prosecutors and crime dramas have sold the American public on the infallibility of forensic DNA. But Pima County Sheriff Chris Nanos let the truth slip: finding DNA on hair is "extremely rare." He told NBC News, "Hair doesn't produce DNA like touch DNA or bodily fluids." That admission cuts against everything jurors have been told in courtrooms across the country, where hair evidence has locked up defendants on the promise that science doesn't lie. It often can't even speak.

Nancy Guthrie was taken from her upscale Tucson suburb of Catalina Hills on Feb. 1. Her doorbell camera captured a masked figure, 5'9" to 5'10" with a medium build, carrying a black Ozark Trail backpack. Despite multiple ransom notes and the combined resources of local and federal law enforcement, authorities have produced nothing consequential. The FBI's Phoenix office confirmed that "all hair had been resolved and it does not point to a suspect."

Nanos told Fox News Digital that investigators sent the hair to a California lab: "It came back…there's no DNA. But does that mean the hair isn't that of the suspect? We won't know that till we have the suspect's hair. You don't just destroy it." The sample was preserved — but its evidentiary value, for now, is zero.

There's more. A mixed DNA sample from the crime scene contains genetic material from up to four different people, according to the Daily Beast. Labs in at least five or six states, including the FBI facility at Quantico, are trying to isolate individual contributors. Whether that's even possible remains an open question.

Nanos has faced mounting criticism over the stalled investigation. In May, he told People magazine the department was "getting closer." On Thursday, he pivoted to optimism about genetic genealogy — using family trees to generate leads. "That's really where some of my optimism is, that I just know that we're gonna get this thing resolved," he said.

Savannah Guthrie, the "Today" co-host, released a video Monday begging her mother's captors to "do the right thing." She described a "nightmare that will not end."

The heartbreak is real. So is the institutional failure. The same forensic methods that can't produce a suspect in this high-profile case have been used to convict Americans with far less scrutiny and far fewer resources. When the science works, prosecutors call it gospel. When it doesn't, they call it a setback. The question isn't just who took Nancy Guthrie — it's how many people are sitting in cells right now because a jury believed hair and DNA were something they weren't.