Mabel Emma Petersen was born in 1888 in Granger, Utah to Nelsen Petersen (from Denmark) and Sarah Grant Petersen (from England.) She was the third of 13 children and the first-born daughter. She was a dress maker by trade. She never married and died at the age of 30.

Mabel died March 23, 1919 from pneumonia and influenza, which was going around at the time. William Bess, to whom (in some records) she is listed as being his wife, died 12 days later of the same illnesses. A posthumous temple sealing (LDS marriage ceremony) was done by-proxy on their behalf in the Salt Lake Temple on April 30, 1919, suggesting William and Mabel may have had plans to marry each other before their untimely deaths.

William Bess was the widower of Mabel's sister Lillie. Lillie Petersen Bess died in February 1918 due to childbirth complications. It is plausible that a romance between William and Mabel may have occurred as the Petersen family helped William care for his infant after Lillie died.

In fact, in her sister Ella's autobiography, Ella mentions Mabel and William Bess, and their deaths:

"I remember my sister Mabel was keeping company with Will Bess at that time and they came over to see me after [my daughter] Barbara was born [February 1919.] And that was the last time I saw Mabel or Will alive because our family at home got the flu. My older sister Mabel died with it [23 March 1919]... We went to the mortuary in Murray and took care of the clothes and everything for Mabel's funeral. When we went there to see her to get the measurements before we could buy the clothes, I didn't know who she was, she was that much changed. [I was told] she had been so frightened that she was going to die. They said that while she lay in her bed, she said she knew she was [dying] because she could see someone coming to get her... I remember what a cold snowy day it was when Mabel was buried; it was cold enough to freeze you, almost. "

Mabel, Lillie, William (and William's first wife Mary Breeze) are all buried in the Taylorsville Memorial Park Cemetery in Taylorsville, Utah.