Jeff, who was active with the Adaptive Training Foundation — a gym dedicated to helping amputees and people in wheelchairs — is survived by his children, Jake, 24, and Rachel, 23.
Texas Governor Greg Abbott explained that the updated count of missing people was compiled from reports made by friends, neighbors, and family members.
Friends and family said they "hoped and believed" he had remained alcohol-free, though they were "uncertain about his state of mind" in the days leading to his death.
His wife, Julia, and their two little sons are still missing, while their daughter — who had been attending a nearby summer camp — is confirmed to be safe.
The heartbroken father shared that he had been searching for his Joyce, 21, and his voice broke at the end of the interview as he asked the public to keep them in their prayers.
Officials found multiple weapons, including another assault rifle and various rounds of ammunition, inside the vehicle, which was registered with Michigan license plates.
Propst's employer Blue Fish Pediatrics initially said that the employee had been suspended, but later confirmed that "the individual is no longer employed" with the practice.
Janie was the great-granddaughter of the late billionaire William Herbert Hunt, who was also the brother of Lamar Hunt, the late founder of the Kansas City Chiefs.
Tarrence, 51, of Midtown Manhattan, traveled to the Turks and Caicos Islands on June 22 for a romantic vacation with his wife of one year before mysteriously disappearing.
On Saturday, the Royal Turks and Caicos Islands Police Force and a private investigator made the grim discovery during an hours-long search for Tarrence.