George Coty Wayman, 18, was arrested on a charge of capital murder, according to a Clay County warrant.
The incident occurred Tuesday afternoon inside a trailer home in the tiny town of Bellevue, near the border with Oklahoma.
Wayman’s three-year-old stepson, Dominic Tra’Juan Castro, was bouncing on the bed when he was shot in the back of the head.
After a 911 call, a helicopter ambulance rushed Dominic to a hospital 40 miles away but it was too late. The boy was pronounced dead Wednesday morning.
Witnesses initially told investigators that Dominic had been bouncing on the bed when he accidentally landed on the gun, causing it to discharge, officials told KDFX-TV.
After further interviews, however, witnesses admitted that Wayman had pointed the gun at the boy and told him if he didn’t stop jumping on the bed he would shoot him, Clay County Sheriff Kenny Lemons told CBS News.
When the boy kept bouncing, Wayman allegedly pulled the trigger.
“Investigators interviewed eyewitnesses in the bedroom at the time of this incident and have determined that Wayman is the individual that pointed and discharged the handgun that caused the death of the victim,” according to the arrest warrant.
Wayman, whose last name is tattooed above his right eye, is currently being held at Clay County Jail.
In addition to the charge of capital murder, he also faces one count of criminal trespass. His bail has been set at $505,000, according to the Dallas Morning News.
Memorials to Dominic appeared on social media after his death, along with calls for a stiff sentence for his stepfather.
The boy’s biological father is currently in prison for multiple convictions and was denied parole in January, according to KDFX-TV.