Having escaped from Bermuda, Duquesne proceeded to New York City, where he found employment as a journalist for the New York Herald and other newspapers by writing adventure stories.
The Second Boer War ended in 1902 with the Boers signing the Treaty of Vereeniging, but with his family dead and because of his war crimes, Duquesne never returned to South Africa.
While in New York, he published a novel in the French newspaper Le Petit Bleu, and two other novels published in South Africa.
In 1908, he was written up in Men of America as a travelling correspondent sent to locations such as Port Arthur (now the Chinese Lüshunkou District) to report on the Russo-Japanese War, Morocco to report on the Riff Rebellion, and to the Belgian Congo (now the Democratic Republic of the Congo) to accompany Sir Arthur Jones on an expedition, but no corroborating evidence has been found.
In June 1910 he married Alice Wortley, an American, but their marriage would end in divorce eight years later.

During the Second Boer War, Duquesne was under orders to assassinate Frederick Russell Burnham, a highly decorated American who was Chief of Scouts for the British Army.
After the war, Burnham remained active in counterespionage for Britain, and much of it involved keeping track of Duquesne.
In 1910, Burnham and Congressman Robert Broussard founded the New Food Supply Society to import useful African wildlife into the U.S. as a solution to a serious American meat shortage, and Broussard selected Duquesne as an expert.
In support of this plan, Broussard introduced H.R. 23261, also known as the American Hippo Bill, which sought the appropriation of $250,000 to import hippopotamus into the Louisiana bayous both as new food source and to control the water hyacinth then clogging southern river systems.
Former President Theodore Roosevelt backed the plan, as did the U.S. Department of Agriculture, The Washington Post, and The New York Times, which praised the taste of hippopotamus as "lake cow bacon".
Duquesne's expert testimony on this subject before the House Committee on Agriculture is recorded in the Congressional Record.
 The bill fell just short of passing and the New Foods organization was disbanded.

During this time Duquesne became former President Roosevelt's personal shooting instructor and accompanied him on a hunting expedition.
He published several newspaper articles on Roosevelt's hunting trip to Africa, safari big game hunting in general, and the heroic accomplishments of white peoples in Africa.
 Duquesne became a naturalized American citizen in December 1913.
Having escaped from Bermuda, Duquesne proceeded to New York City, where he found employment as a journalist for the New York Herald and other newspapers by writing adventure stories. The Second Boer War ended in 1902 with the Boers signing the Treaty of Vereeniging, but with his family dead and because of his war crimes, Duquesne never returned to South Africa. While in New York, he published a novel in the French newspaper Le Petit Bleu, and two other novels published in South Africa. In 1908, he was written up in Men of America as a travelling correspondent sent to locations such as Port Arthur (now the Chinese Lüshunkou District) to report on the Russo-Japanese War, Morocco to report on the Riff Rebellion, and to the Belgian Congo (now the Democratic Republic of the Congo) to accompany Sir Arthur Jones on an expedition, but no corroborating evidence has been found. In June 1910 he married Alice Wortley, an American, but their marriage would end in divorce eight years later.
During the Second Boer War, Duquesne was under orders to assassinate Frederick Russell Burnham, a highly decorated American who was Chief of Scouts for the British Army. After the war, Burnham remained active in counterespionage for Britain, and much of it involved keeping track of Duquesne. In 1910, Burnham and Congressman Robert Broussard founded the New Food Supply Society to import useful African wildlife into the U.S. as a solution to a serious American meat shortage, and Broussard selected Duquesne as an expert. In support of this plan, Broussard introduced H.R. 23261, also known as the American Hippo Bill, which sought the appropriation of $250,000 to import hippopotamus into the Louisiana bayous both as new food source and to control the water hyacinth then clogging southern river systems. Former President Theodore Roosevelt backed the plan, as did the U.S. Department of Agriculture, The Washington Post, and The New York Times, which praised the taste of hippopotamus as "lake cow bacon". Duquesne's expert testimony on this subject before the House Committee on Agriculture is recorded in the Congressional Record.  The bill fell just short of passing and the New Foods organization was disbanded.
During this time Duquesne became former President Roosevelt's personal shooting instructor and accompanied him on a hunting expedition. He published several newspaper articles on Roosevelt's hunting trip to Africa, safari big game hunting in general, and the heroic accomplishments of white peoples in Africa.  Duquesne became a naturalized American citizen in December 1913.
Fritz Joubert Duquesne