[1][2] Ketcham attended public school in Indianapolis until age thirteen when he studied for two years abroad in Germany.
He remained a student at the college until February 1864, when he enlisted, joining Company A of the 13th Indiana Infantry Regiment.
[1][2] Following his time in the Union Army, Ketcham began attending Dartmouth College in Hanover, New Hampshire, graduating in 1867.
He was admitted to the bar in 1869 and began practice with his father and James L. Mitchell (who later served as Mayor of Indianapolis).
As Attorney General, Ketcham broke up a notorious ring of gamblers at the Roby horse racetrack in Hammond, successfully convinced the Indiana Supreme Court that apportionment laws passed in 1893 and 1895 were unconstitutional, and represented the state in a case against the Chicago and Eastern Illinois Railroad regarding unpaid incorporation fees.
He retired at the next annual encampment, also in Indianapolis, one year after his election, succeeded as commander-in-chief by Lewis Pilcher.
He gave a particularly controversial speech at an encampment in Boston, during which he promoted the Americanization of immigrants to the United States.
The Boston crowd so poorly received his remarks that forty members of the Massachusetts General Court signed a statement decrying Ketcham's address.
He similarly condemned a meeting of German sympathizers in Madison Square Garden during the First World War and further promoted Americanization and nationalism in a speech at the Cadle Tabernacle.
His parents were associated with the Second Presbyterian Church of Indianapolis, and Ketcham was baptized by the famous clergyman and abolitionist, Henry Ward Beecher.