In answer to your hopes. Information from the Probable Cause Statement:
The next morning, authorities said, he returned to scrub the scene.
Police said he put the child in the truck with her dead parents, drove them into the woods and then shot and killed the child.
“He then took [the child] out of the vehicle,” according to the probable cause statement. “He eventually held her in his arms, with her facing away from him, and shot her in the back of the head.
“Atchison admitted to investigators he shot the weapon three times. On the first shot, the weapon malfunctioned. On the second shot he missed the child, and the third shot struck her.”
https://www.washingtonpost.com/news...-the-woods-police-say/?utm_term=.ecf0fb38a82c
I read the Probable Cause Statement filed with the Court. I was on a FB page of a family friend so I did not link it. All in all he confessed right away when authorities found the truck at this brothers house where he parked it.