Melva Jean O'Neill (née Davis) was born on October 21, 1951, in Carlsbad, New Mexico. Melva married Layton on December 19, 1979. Melva had one child going into the marriage: Amy and Layton had five children going into the marriage: Marilyn, Colleen, Mike, Jenny, and Dennis.

O'Neill was employed as a homemaker but had previously worked as a waitress and motel desk clerk.

John Chapman Hopkins was born on June 30, 1933 in Palo Alto, California. John married V. Adele on June 14, 1954 and had two children: Anna Adele an Barbara Ellen.

Hopkin was a scientist and test director as the J-division leader for the Nevada Test Site. In 1955 and 1956, Hopkins was a Los Alamos summer student.

Hopkins obtained a doctor of philosophy degree in physics from the University of Washington in 1960.

From 1960 to 1993 Hopkins was employed at the Los Alamos National Laboratory (LANL).

Aaron Williams was born October 4, 1921 in Tatum, Texas and spent his early adult years in Detroit, Michigan working for the Chrysler Corporation. He joined the Army in 1940. Williams moved to Las Vegas from Detroit, Michigan, after serving in the military. He worked at the Nevada Test Site, then ran for local office in the City of North Las Vegas city council. He later was elected to the Clark County Commission.