Cox was executed for his crimes in 1944. What I found in my internet search were his death certificate and a few lines in a book review, which tell essentially of the same incidents as the comic story.
It's a terrible tragedy when a man kills his estranged wife. It's inexcusable. Unfortunately it happens and the cases usually make the headlines, but as far as I know Cox is the only man in Utah ever put to death for the crime. Killing the judge who granted the divorce might have had something to do with it. (I doubt the way the divorce is depicted as taking place over a telephone call to the judge from Cox's wife.)
Along with murder cases, [Judge] Trueman handled the usual divorce cases. One was that of Austin Cox Jr. Cox didn't like the outcome, and on the night of July 24, 1943, went hunting for his wife.
He'd heard she was staying at a house at 2240 Lincoln Ave. (now the site of a home improvement center) and went there. She wasn't there but six other people were and he shot them, killing four and wounding the rest.
Then he drove to 1543 27th St., Trueman's home, and fired a shot at a kitchen window. Trueman and his wife, in a second story bedroom, turned on a light and went to a window to see what was going on, and Cox shot him.
Cox was executed a year later.
The Unforgiven, Utah's Executed Men by L. Kay Gillespie
Utah was also the answer to a trivia question that went around for years: "What's the only state in the U.S. where a prisoner gets a choice for his execution?" Why, Utah, of course, where the condemned could choose hanging or firing squad. The trivia questions usually leave out the choice of decapitation. It was only offered for a time and never chosen by any condemned man. Nowadays the law has been changed and there are no more choices, only lethal injection.
I assume firing squad seemed better than hanging, because most murderers chose it. At least it was quick, but good god, what a choice. I would say you're in a very bad way when the last decision you're allowed to make is, "Do you want to die dangling from a rope or strapped into a chair with a paper target pinned over your heart?" Uh, can I instead choose 'dying of old age'?"
From Crime-Fighting Detective #14, 1951: