Frank John Wilson (May 19, 1887 – June 22, 1970) was best known as the Chief of the United States Secret Service and a former agent of the Treasury Department's Bureau of Internal Revenue, later known as the Internal Revenue Service. Wilson most notably contributed in the prosecution of Chicago mobster Al Capone in 1931, and as a federal representative in the Lindbergh kidnapping case. Early life Frank J. Wilson was born in Buffalo, New York, on May 19, 1887. During World War I Wilson served for the United States Army for a brief stint before being honorably discharged in 1919 due to poor eyesight. In the same year Wilson became the Chief New York State Investigator for the United States Food and Drug Administration. This was short lived as Wilson then worked for the Department of Justice Fair Price Commission in 1920. In the same year Wilson took the opportunity to work for the United States Department of the Treasury as part of the Internal Revenue Bureau's intelligence unit until 1936. During this time Wilson helped on the Al Capone investigation, the Lindbergh kidnapping, and the Huey Long assassination. Overall, not much is known about Wilson's early life other than his career due to lack of information. Capone investigation Upon joining the United States Treasury Department's Intelligence Unit in 1920, the former accountant Wilson would earn a reputation throughout Prohibition as a thorough, if not obsessive, investigator of tax returns and income."[Wilson] fears nothing that walks. He will sit quietly looking at books eighteen hours a day, seven days a week, forever, if he wants to find something in those books." - Elmer L. Irey"[Wilson] sweats ice water" - Suspect who was interrogated by Frank J. WilsonIn January 1929, an investigation conducted by Prohibition agents under Alexander Jamie (including Jamie's brother-in-law, Eliot Ness) into bootlegging in Chicago Heights uncovered evidence indicating that Al Capone's brother Ralph had not paid taxes on a sizable illegal income. The 1927 Supreme Court decision in United States v. Sullivan having already established that any criminal activities that yield an income are subject to income taxes, the Intelligence Unit of the Bureau of Internal Revenue headed by Elmer L. Irey began to build tax evasion cases against leading figures in the Chicago Outfit, with the ultimate goal of convicting Al Capone. In April 1930, their efforts resulted in Ralph Capone's conviction for tax fraud,