The couple was traveling through St. Tammany on the way to Texas in the early hours of February 22, 2014, when their car ran out of gas. The pair began arguing, and Nall called his mother to ask for money. Nall’s mother became so concerned that she alerted the St. Tammany Parish Sheriff’s Office, which dispatched deputies to conduct a welfare check on the couple at a grocery store parking lot on Highway 21 about 1:38 a.m. The deputies allowed the couple to leave after about 45 minutes.
Hours later around noon, officers encountered Nall again at a gas station in Covington, where he held a gun to his head, threatened to kill himself and caused a two-hour standoff with deputies. The event ended when Nall fired the unloaded gun, and deputies subdued him with bean-bag rounds. Meanwhile, Denny was reported missing, and five days later her body was discovered in a wooded area off Brewster Road near Covington.
Prosecutors also showed jurors a videotaped confession from Nall, who eventually admitted to arguing with Denny, retrieving a knife, and pretending momentarily to be sleeping in the front seat of the car, before leaping into the back seat and stabbing her repeatedly. A medical expert testified that Denny was stabbed 12 times in the back and that from the appearance of the wounds, she most likely had been sleeping before the attack.
Nall’s attorneys did not dispute that he killed her, but they argued that he was insane and did not understand what he was doing—a claim that was refuted by prosecutors. Prosecutors told jurors that Nall was indeed psychotic but that his mental state was self-induced from taking drugs, which does not meet the legal criteria for an insanity defense. They pointed to Nall’s meticulous efforts to cover up his crime—hiding the body, hiding the knife, hiding his Jeep, washing his bloody hands, changing clothes, contacting family members to assist him in getting out of town after the crime—as proof that he knew right from wrong.