It's amazing how much you can learn years later about evidence that's been right under your nose all along.
Remember JonBenet Ramsey? For years, I thought her mom had something to do with her death. Fortunately, I wasn't a grand juror. Because it turns out I was wrong.
On Wednesday, the district attorney in charge of the case sent a letter to JonBenet's father. "We became aware last summer that some private laboratories were conducting a new methodology described as 'touch DNA,'" says the letter. It describes a technique in which "forensic scientists scrape places where there are no stains or other signs of the possible presence of DNA to recover for analysis any genetic material that might nonetheless be present." Using this technique, a lab hired by the D.A. has managed "to develop a profile from DNA recovered from the two sides of [JonBenet's] long johns." It matches the profile obtained from DNA on the crotch of her underwear.
"The match of male DNA on two separate items of clothing worn by the victim at the time of the murder makes it clear to us that an unknown male handled these items," the D.A. concludes. For this, "there is no innocent explanation." Accordingly, she declares that the Ramseys are no longer "under any suspicion."* The evidence of their innocence was in our hands all along. We just didn't have the technology to see it.
That's not the only such discovery announced this week. Here's another: According to press releases from Brown University and the Carnegie Institution, scientists have just "found evidence of water deep within the Moon." Did we get it by sending up a new lunar mission? No. "The water clue came from lunar volcanic glasses, pebble-like beads collected and returned to Earth by NASA's Apollo missions in the late 1960s and early 1970s." Those beads have been sitting under our noses for 40 years. We found the evidence by developing and applying "new methods for analyzing lunar samples"—specifically, a refinement of secondary ion mass spectrometry. The official report is published in Nature.
I'm glad we didn't have to launch a whole new lunar mission to find what we found in the Apollo beads. But I'm far more relieved that the Ramseys weren't sent to jail for a crime in which they played no part. Others haven't been so fortunate. Hundreds were put away for crimes in which new evidence—DNA—now appears to have cleared them. According to the Innocence Project, DNA has already exonerated 218 U.S. convicts. Sixteen of them had been sent to death row. The evidence of their innocence was under our noses all along. We just didn't see it or use it.
I was about to write that we haven't yet executed anyone exonerated by DNA. But that's the wrong way to write the sentence. Here's the right way: We haven't yet exonerated by DNA anyone we've executed. The discovery comes after the act. In the case of the Apollo missions, the evidence waited 40 years. The Ramseys had to wait 12 years, long enough for JonBenet's mother to die while still under suspicion. But at least they weren't in jail. The Innocence Project reports: "The average length of time served by exonerees is 12 years. The total number of years served is approximately 2,694."
What's really scary is that those 218 people were lucky. None of them had been put to death.
Viscerally, I support the death penalty. I think there's such a thing as deserving to die. But our pattern of discovering evidence right under our noses long after the fact should humble us about killing people. Do you think "touch DNA" is the last technology we'll discover in criminal forensics? How confident are you that none of the 1,100 people we've executed will end up being exonerated by a technology we didn't use or possess at the time?
The lesson of the Ramsey case and the moon beads is that you never have all the evidence, even when it's right in front of you. There's always more to be learned from a technology you haven't yet tried. You still have to make the best judgment you can at the time. You can't expect that judgment never to be corrected. But you have to leave it open to correction.