A note, a payment and a record
Charles Augustus Lindbergh Jr., aged 20 months, was taken from his family’s home near Hopewell, New Jersey, on March 1, 1932. The FBI history describes a ransom note found at the nursery window. A ransom was later paid, and the child was found dead in May.
The money created a trail because investigators had recorded the serial numbers of the bills. Currency can pass through many hands. A recorded serial number allows a recovered bill to be identified individually, even after it has left the person who first received it. That made the records of the payment useful long after the exchange.
From one bill to a suspect
The FBI account describes how a ransom bill used at a filling station helped investigators trace a vehicle and identify Bruno Richard Hauptmann in 1934. Investigators found additional ransom money. Those steps are distinct: the number identified the bill, information from the transaction directed attention toward a person, and the search supplied further evidence.
The trial brought several strands together. Hauptmann was convicted in New Jersey in 1935. An account that jumps directly from a serial number to a verdict misses the other evidence needed to connect possession of the money to the crime itself.
The federal role changed during the investigation
The FBI chronology also tracks how federal officials assisted state investigators and how Congress enacted a federal kidnapping law in 1932. Keep that legislative history separate from the New Jersey trial. One concerns the powers available for investigating kidnappings. The other concerns the evidence and decision in a specific prosecution.