I’m often just as surprised by what forensic scientists can’t do as by what they can. In the Netflix documentary Making a Murderer, for instance, the question of whether police planted the main character’s blood at a crime scene comes down to whether or not the FBI can detect a common laboratory chemical called EDTA in a bloodstain.

On a TV crime show, this would be a snap. The test would take about five minutes and would involve inserting a swab into a magic detector box that beeps and spits out an analysis of every substance known to humankind.

In real life, there’s no common and accepted test in forensic labs for EDTA even today, nine years