Before the 1900s, solving a murder was done using conjectural theories or flimsy psychological notions of what makes a killer a killer. That all changed with the development of forensic techniques employed at crime scenes, but few know the origin story of these now taken-for-granted methods of solving murders and other misdeeds.

It all changed with the revolutionary contributions of Edward Oscar Heinrich who pioneered many of the forensic techniques used today. Today’s guest is Kate Dawson, author of the book American Sherlock, who gives Heinrich his due with an account of his work on some of the most perplexing and notorious cases of the first half of the twentieth century. The press at the time dubbed Edward Oscar Heinrich ‘America’s Sherlock Holmes’ thanks to his brilliance in the lab, his cool demeanor at crime scenes, and his expertise in the witness chair. He invented new forensic techniques. A CSI in the field and inside the lab before the acronym existed. And he was a nascent innovator of criminal profiling fifty years before the FBI’s Behavioral Science Unit invented its methodology.

Never a member of a police force, Heinrich was brought in to consult on many high profile cases, including the legendary rape and manslaughter trial of movie comedian Roscoe “Fatty” Arbuckle (a case the prosecution ultimately lost when the jury neglected to accept Heinrich’s finger print evidence). Bloodstain pattern analysis, ballistics, the use of UV rays to detect blood, hair and fiber evidence, handwriting analysis—all were virtually unheard of methods that Heinrich employed to bring criminals to justice. Often the cutting-edge techniques that Heinrich engaged in the lab and brought to the courtroom as an expert witness would rile the authorities, even as they galvanized the public.

Edward Oscar Heinrich quietly and unassumingly offered a revolutionary approach—the immutable proof that science and reason could provide to the thrilling, often messy world of crime solving.