Forensic science as a holistic discipline was developed in Austria in the late 19th century by Hans Gross. As an internationally well-connected researcher, he shaped the development of forensics worldwide. However, it appears that Gross appreciated one American colleague particularly: John H. Wigmore, Professor at the Northwestern University Chicago, who was also a highly influential character and laid the foundation of the modern American law of evidence. The appreciation was mutual but their relationship and influence on the development of criminal sciences on both sides of the Atlantic were never studied. Therefore, the presented archival research investigates this transatlantic relationship and its potential impact on the field.