- "You had your own men, soldiers, brothers walk into a trap?"
"And I'll carry that with me 'till the day I die. But 'till that day comes, I'm going to be a very, very wealthy man."
"You swore an oath, man!"
"Then Genesis day happened! ISIS, Taliban, Al Qaeda. I can take them all on, but what hope does the world have against men with magic? Or those meta-humans in Central City? How long before one of them manages to tear the world apart?"
- —John Diggle and J.G. Walker[src]
Walker's crimes were ultimately exposed, leading to him and his accomplices being incarcerated in a military prison.
Sometime after Genesis Day, Walker became the leader of John Diggle's unit while John himself was stationed in Eastern Europe. The unit mission was to recover a nuclear weapon which was stolen by terrorists, but after recovering it, Walker and other rogue soldiers betrayed John, framing him for the murder of a fellow soldier. He then fled the scene, with the nuke.
When John was arrested once again, after Prometheus tipped the feds, Walker wanted John to be transferred, so that he could be killed during the transfer, but Adrian Chase, who was serving as John's lawyer, managed to delay John's transfer by making John punch him.
After Walker crimes were exposed by Felicity Smoak with the help of Helix, Walker and his loyal men fled to Russia to sell the nuke to the Markovian terrorists, but they were ultimately stopped with the intervention of Team Arrow and the Bratva. He was then arrested by A.R.G.U.S., which placed him under custody so that he could be judged for his crimes.
Walker displayed a great lack of empathy, being capable of killing fellow soldiers just to frame John Diggle or selling nukes to terrorists for his own sake.