Warning: This episode contains details of gun violence.  The gangster era of the 1920s led to breakthroughs in firearms used as evidence in criminal trials. But many studies now show that matching cartridge casings from a crime scene leaves room for human error. And for Odell Adams, the questionable reliability of firearms analysis put him on trial twice for the same crime.  CSI On Trial is a co-production of iHeart Podcasts and School of Humans. It is a Curiosity Podcast based on the Curiosity Stream series CSI On Trial. You can watch all six episodes of the video series here if you sign up for Curiosity Stream. See omnystudio.com/listener for privacy information.