Dubois' health did not improve, however, and in late December 1901 he asked to be transferred to an executive branch department. Stone was appointed Chief Usher on January 2, 1902, after Dubois' request for a transfer was approved. Stone was the first individual to have the official title of "Chief Usher" bestowed on him throughout his tenure. In 1902, the usher staff was greatly expanded. The North Portico was closed as a public entrance and now served only for official guests and visitors. The usher's office, which was adjacent to the Entrance Hall, no longer could control the influx of visitors, so the usher staff, as well as White House police force, was almost doubled to handle the new duties. Stone supervised the dozen or so "inside" officers on the police force. Stone left the Chief Usher's position on March 5, 1909, when he was appointed Doorkeeper to the President of the United States. He replaced Major Charles D.A. Loeffler, who had been Doorkeeper since 1869. Leading Prohibition enforcer Stone left the White House in 1912 due to poor health, and became an Internal Revenue agent with a roving commission with the United States Department of the Treasury. In June 1915, Treasury agents discovered that Knox Both, an Internal Revenue agent in Tennessee, had stolen more than $383,000 in alcohol tax revenues and helped protect an illegal liquor production syndicate that generated more than $2 million a year. Stone was assigned to track him down. He succeeded in doing so (although Booth died of a heart attack before standing trial). For the next five years, Stone was often assigned the toughest cases, or those in which high-ranking criminals had fled. The Washington Post called him "the Javert of internal revenue". Prohibition was enacted in the United States in 1919, and in 1920 Stone moved into a law enforcement role, helping to enforce the Volstead Act. When Prohibition took effect, it was initially enforced by the Bureau of Internal Revenue (BIR) in the Department of the Treasury. A Commissioner of Prohibition was established to oversee enforcement efforts within the BIR, and the nation was divided geographically into 12 enforcement districts. An Assistant Secretary of the Treasury coordinated the enforcement efforts of the BIR, the United States Customs Bureau, and the United States Coast Guard. Each U.S. state was given the authority to supervise legal production of alcohol (such as low-alcohol beer