Our conception of how many Americans have been wrongly imprisoned has changed drastically since the first DNA exoneration in the United States, in 1989. Again and again, DNA evidence has demonstrated beyond a doubt that people were convicted of crimes they didn’t commit based on unreliable eyewitnesses, bad forensic science, and prosecutorial misconduct. But such evidence is not available in many cases that otherwise have the markers of potential exonerations—because convicts don’t have the resources to track it down, because investigators failed to collect it from the crime scene, or because there was simply never any such evidence to collect in the first place. While non-DNA exonerations are on the rise—there were 152 in 2016—that number remains vanishingly small compared with the ranks of the wrongly imprisoned. Simon Cole, a criminology professor at UC Irvine and the director of the National Registry of Exonerations, estimates that thousands—possibly tens of thousands—of innocent men and women may have been convicted.

McCloskey believes that Benjamine Spencer is one of these convicts. Had investigators found sufficient biological evidence at the crime scene, Spencer might have hoped that it would eventually point to another suspect, and irrefutably establish his innocence. But no such evidence emerged, leaving Spencer to walk a narrow path to exoneration.