Proznanski was a member of SSG Michael Daly's squad. On October 23rd, the squad was en route to West Stockbridge. Near Concord, the Vertibird carrying the squad was hit by the EMP, known as the Great Blackout, from the nuclear blasts that struck the Greater Boston area and crashed into the roof of the Museum of Freedom. The co-pilot died on impact, while the pilot died from his injuries a day later. The following day Flaherty and Kanawa were shot and killed by panicked survivors. After the death of his squadmates, Proznanski simply left on his own, never to be seen again.
Proznanski is mentioned only in Fallout 4.