Jordan later said he became alarmed at the extraordinary amount of supplies and unusual diplomatic immunity cargo going through Great Falls, Jordan began spying by keeping a detailed "diary" (actually three ledgers) in which he registered all he could discover about the Lend-Lease cargo.
In 1944, Major Jordan returned to business, and although he had a sideline as a public speaker, he attracted little attention until 1949 when interest in Soviet nuclear espionage was at its peak.