Theesfeld pleaded guilty to first-degree murder in August 2021, admitting that he was the one who shot Kostial to death at Sardis Lake in Oxford, Miss., in July 2019.
Theesfeld and Kostial had a “complicated” relationship.
According to People, Kostial and Theesfeld met as they both attended Ole Miss. A former housemate of Kostial’s told the magazine in 2019 that Kostial and Theesfeld “had a complicated relationship, an on-and-off one, but at no point did she say he was her boyfriend.”
A friend of Kostial, meanwhile told People that Theesfeld was “super misogynistic” and would “have six girls around the table, and he’d sit back and laugh at them, like a pig.”
Investigators found text messages from Theesfeld on Kostial’s Apple Watch.
The investigators then uncovered details about Kostial’s tumultuous relationship history with Theesfeld, including the photo of the inconclusive home pregnancy test she sent him that April. Kostial asked Theesfeld to meet in person to talk over the situation. Finally, he agreed the night before the murder.
Theesfeld was caught in Memphis after he bailed on a questioning.
Investigators tried to bring Theesfeld in for questioning, but he was a no-show, so a bulletin for his arrest was issued. Memphis police found Theesfeld at a gas station hours later, and they reported that he had blood on him and a gun in his truck that matched the caliber of the murder weapon.
In August 2019, Theesfeld was charged with capital murder and faced the death penalty, but that charge was later reduced to murder in the first degree, according to The Oxford Eagle. Having pleaded guilty to that reduced charge, Theesfeld was given the mandatory sentence of life in prison, though he’ll be eligible to petition for a conditional release at the age of 65, the newspaper adds.
Kostial’s mother called him a “sinister and violent and corrupt monster.”
At the plea hearing, Theesfeld apologized to the Kostial family but didn’t reveal his motive. “I am sincerely sorry for the pain I’ve caused while taking Ally from you,” Theesfeld said, per the Eagle. “My actions have forever changed your lives and my family’s lives. I wish I could take it all back, but I can’t. There is no excuse for my actions, and I have asked God for forgiveness. I hope one day that you will find it in your heart to forgive me.”
Kostial’s mother’s statement at the hearing, meanwhile, conveyed her and her family members’ grief. “I wish I could have kept her away from this evil, callous, scheming, ungrateful, sinister and violent and corrupt monster,” she wrote. “He had every opportunity to do good in the world, but he chose to do evil. Brandon, you belong in jail each day for the rest of your life for the heinous act you committed to such a sweet soul in Ally.”
Now 48 Hours and Michelle Miller, co-host of CBS Saturday Morning, are covering the case in “What Ally Kostial Didn’t Know,” the episode airing tonight, Saturday, March 5. “Prosecutors say this case raises questions about missed warning signs in relationships and whether the murder could have been prevented,” CBS says in a press release.
48 Hours airs Saturdays at 10:00 p.m. ET on CBS and streams anytime on Paramount+.