Between March and April 1851, three years after the "Badian Revolution", his mother Eva Katharina née Fischer, emigrated with her still living eight children (six had already died) to Lancaster, Pennsylvania.

[11][12][13]: 46 In February, April, and May 1877, Sieber acted as a guide for Pima County Marshal Wiley Standefer, who was pursuing outlaws in the region.

Sieber was Crook's lead civilian scout and mentor to Tom Horn, whom he taught to speak German, as well as fighting together during the battles at Cibecue Creek (August 1881), and Big Dry Wash (July 1882).

[15] Sieber was in the field but not present when the Apache leader and renegade Geronimo surrendered to young Lt. Charles B. Gatewood (1853-1896), and commanding General Nelson Miles (1839-1925), in September 1886, finally ending the Indian Wars in the old Southwest.

[16][notes 2] A few days after the Apache Kid surrendered, he was found guilty of mutiny and desertion and sentenced to ten years at the military prison on Alcatraz Island in San Francisco Bay, California.

The then U.S. Secretary of War, William Crowninshield Endicott reviewed the court-martial file of the Apache Kid and came to the conclusion that the trial had not been fair.

Unhappy with military law, Sieber decided to retry the Kid, this time for attempted murder in the local territorial court.

The project was under the supervision of another famous frontier scout, "Yellowstone" Luther Kelly at Apache Trail, a separate downstream road, Maricopa County, Arizona.