His mother, Lori Ponce, told the Fort Worth Star-Telegram that her son does not have a history of mental illness but has recently been under a lot of stress.
"Brent is not a demon. ... He loves that boy," Ponce said. "Something happened. Don't paint him as some crazy man. No, that's not him."
His stepfather told the newspaper that Bartel was "deep into the Old Testament" and may have convoluted some biblical references about Passover, a weeklong Jewish commemoration of the deliverance of the ancient Hebrews from slavery in Egypt that occurs in March or April.
"If you know about the Old Testament, there's the Passover marks on the door frame (that) were done with a sacrificial lamb, definitely not sacrificial children," John Ponce said.
As officers were headed to the scene after Bartel's chilling call, a neighbor also called 911, saying a woman was outside her door and telling her something was going on at her house. The child's mother could be heard on the recording saying, "He's trying to hurt my 6-year-old" and "Please hurry! Oh, God!"
When the dispatcher talked to the boy's mother directly and asked whether her husband had weapons, she said she had taken one knife but there were a lot of knives in the house.
Richland Hills police have responded to a few domestic calls involving verbal arguments at the home in the past four or five years, Stringer said.