John Shannon Coogan was born on September 29, 1928, in North Hampton, Massachusetts. John married Betty Jean on August 16, 1952, and they had two children: John III and Sharon.

Coogan was enlisted in the United States Marine Corps.

Coogan attended the University of New Mexico.

Coogan is affiliated with the Nevada Test Site as part of Reynolds Electrical & Engineering Co (REECO); USPAS; and Environmental Protection Agency (EPA).