Born in Pittsford, New York,[1] Merrell served in the American Civil War as a soldier and a military correspondent.
[2][1] In the wake of the Great Chicago Fire in 1871, Merrell "moved to Laramie and later Rawlins, Wyoming", where he "built a large practice and invested in real estate".
[1] He served as a was County and Prosecuting Attorney of Carbon County, Wyoming, for seven terms of two years each, also serving as Wyoming's Commissioner to the New Orleans Exposition,[1] and president of the Rawlins Board of Trade.
[2] In 1890, Merrell ran for a seat in the U.S. Senate, but was instead accepted an appointment by Governor Francis E. Warren, on November 24, 1890, to a seat on the Wyoming Supreme Court vacated by the resignation of Chief Justice Willis Van Devanter.
He entered the State Hospital in Evanston, Wyoming, shortly thereafter, where he remained until his death.