He was born in about 1842 in Monticello, White County, Indiana. He had nine known full siblings and two half-brothers (from his father’s second marriage). He was married to Minnesota “Minnie” Elizabeth Foster on 11 June 11, 1879 at Cottoneva (now Rockport),California. Minnie was a daughter of William McFadden and Sarah Ann Charlotte (Murphy) Foster, survivors of the Donner Party. Robert and Minnie had five known children: 1) Robert Bruce Markle, Jr. who married Elizabeth BALLASHOFF Bloch; 2) Elizabeth M. (Markle) Richardson; 3) Henry-Harry Alfred Markle; 4) Charles-Carl Oliver Markle; and 5) Margarite Love Markle. Any surviving biological descendants would come from their daughter Elizabeth. Sometime prior to 24 May 1910 he and his wife were separated and presumably divorced, as he was indicated to be a widower in the 1910 Census enumerated on that date. His wife was similarly indicated to be a widow in the 1920 Census enumerated on 6 Jan 1920, which was four months prior to his death.
Susan E. (Bloch) English, a step-daughter of his son, Harry Alfred Markle, noted before her death that she knew him to be buried in Hillside Cemetery. His name is also engraved on a marker in the Markle family plot at Rose Memorial Park in Fort Bragg, California, but it appears that it was added by one or more of his children as a cenotaph.
His obituary in the 30 Jun 1920 edition of the Fort Bragg, Mendocino County, CA Advocate reads, “R. Bruce Markle died in Alaska May 28, 1920 at the age of 78. He had once been the Mendocino County surveyor and a civil engineer with the Union Lumber Company in Fort Bragg. The railroad tunnel at Fort Bragg was built under his supervision.”