“Baby Face” Nelson is one of the most notorious gangsters in FBI history. He was a callous killer with a violent temper who participated in a countless number of robberies and was responsible for the deaths of three FBI agents—more than anyone in history—as well as the deaths of numerous other law enforcement officers.

Baby Face Nelson’s body armor was recovered on November 27, 1934, after the shootout in Barrington, Illinois, that resulted in the death of FBI Special Agent Herman Edward Hollis and ended Nelson’s life.

https://www.fbi.gov/history/artifacts/baby-face-nelson-body-armor