Andrew Witt, a former senior airman, was convicted in 2005 of a double homicide, and was later sentenced to life without parole.
At least 92 veterans will be part of the 118th Congress next year.
Only 91 veterans were elected to House and Senate seats in 2020.
The technical sergeant entered a guilty plea to parading, demonstrating or picketing in a Capitol building and will be sentenced in November.
