As a member of the Republic Army, specifically an officer, Decker existed during the time of the Galactic War. He was a Provost in the Dead Man's Legion in 3642 BBY; this Legion was a specialized unit within the Republic Army comprised of criminals. On a mission to Nar Shaddaa sanctioned by Supreme Chancellor Jebevel Madon, Decker, along with fellow Provost Marshal Fideltin Rusk, oversaw the Legion; during this time Rusk sent Private Merghal to Decker for processing.