William Logan Rynserson was born on February 22, 1828 in Mercer County, Kentucky. He was the eldest of 13 siblings born to Baptist Reverend John Reynerson and Elizabeth Cunningham. When he was two years old, the family relocated to Clayton, Indiana in 1830 where his father became the town’s Reverend. It was around this time the family seemingly took an E out of the spelling of the last name. Possibly for pronouncing. Rynerson is believed to have studied at Case Western Reserve University in Ohio where he met Samuel B Axtell and became close friends. In his twenties, Rynerson journeyed to California to try his hand at mining, likely traveling by horseback with friends, including Samuel B. Axtell.

During his time in California, Rynerson enlisted in the Army when the Civil War erupted. The Amador County recruitment centers accepted him on August 1, 1861, and he quickly rose to 1st Sergeant. Rynerson joined the California Column and marched through the desert to New Mexico, where he earned the rank of First Lieutenant on August 6, 1862. Following his discharge from the California column, Lieutenant Rynerson chose to serve in the US volunteers and made captain.
While serving at Fort Bayard, New Mexico, Captain Rynerson was brevetted as a Lieutenant Colonel on March 13, 1865. He was later mustered out of the Quartermaster Department of the US Volunteers on November 30, 1866. Afterward, Rynerson took on the role of postmaster of the sutlers at Fort Bayard until 1870 when he resigned and moved to Las Cruces. Here Rynerson re-engaged in mining in the Organ Mountains and built a silver mill. Mr. Rynerson acquired some property and began a small ranching/farming operation and met a young lady. 
In December 22, 1872, William Rynerson wed Luciana Pope, with whom he bore six children. Roughly three years later, Rynerson was designated as the district attorney of Dona Ana county. The appointment was granted by his associate, Samuel B. Axtell, who had just been installed as the Governor of New Mexico Territory under President Grant. Work would be conducted at neighboring town Mesilla. Whether Rynerson knew it or not he was now in the pocket of the notorious Santa Fe Ring.