Edward Lee Bedwell confessed to the Grimes murders, was arrested and charged, and was ultimately released when his confession failed to hold up. Investigators noted that many details in his confession matched published newspaper accounts rather than undisclosed case facts. If you were reconstructing the 1957 investigation, what specific investigative procedure — standard today but inconsistently applied in 1957 — would have most efficiently separated Bedwell's genuine knowledge from his newspaper-contaminated claims?