Woman who shot and killed boyfriend says she didn't know her gun had a bullet in the chamber

Mary Katherine Higdon of Griffin, Georgia, was arrested for the murder of her live-in boyfriend, Steven Freeman. Was the shooting an accident, or does the forensic evidence suggest that she methodically planned to kill him? CBS News correspondent David Begnaud investigates for "48 Hours" in "The Case Against Mary Katherine Higdon." 

Late on the evening of Aug. 1, 2018, the Griffin Police Department responded to a frantic 911 call from 24-year-old Mary Katherine Higdon. She told the dispatch operator that she had just shot her boyfriend, by accident. During the call, she stated that she didn't know the gun had a bullet in its chamber.

When first responders arrived at the couple's home, paramedics attended to Steven's life-threatening injuries, while police spoke with the distraught Higdon and secured the scene.  Steven Freeman was rushed to the hospital, but the 23-year-old died just minutes before midnight.

At the chaotic scene, Higdon said the gun went off accidentally, as she was handing it to Freeman. But investigators noticed food strewn across the kitchen floor, which lead them to believe that there may have been an altercation before the shooting.  Police began to suspect that this was more than just an unfortunate accident.

Higdon was escorted to police headquarters to be interviewed.

There she told investigators a different story, saying the gun went off when she was tossing it to Freeman.  The interview quickly turned into an interrogation, and investigators say Higdon suddenly confessed to murder, admitting she shot Freeman in anger.

Believing they had an ironclad confession on tape detectives arrested Higdon for the murder of Steven Freeman.

But there was a big problem. There was nothing but feedback on most of the recording. Prosecutors would have to try to make their case without it.

At her June 2019 trial, prosecution witness Thomas Skinner testified that Higdon sold guns at the same sporting goods store where he also worked for a time. "I know she knows how to handle a gun very well," Steven's friend told the court. Thomas Skinner went on to say that Higdon was raised around guns and bragged about her knowledge of firearms to Freeman and his friends.

Higdon took the stand in her own defense. She tearfully testified that  Freeman was the love of her life and that she never wanted to hurt him. Higdon was emphatic that the shooting was an accident and that she didn't know that the gun had a bullet in its chamber and was primed to fire.

The prosecution showed the jury two exhibit photos that revealed close-up details of the weapon used to shoot Freeman. A Griffin police sergeant also testified that the gun looked wet when he examined it, and that there also appeared to be cooking grease on the gun.

During her interview with CBS News correspondent David Begnaud, prosecutor Kate Lenhard summarized her case for how and why she believes Higdon killed Freeman. Lenhard told the jury that the relationship between Freeman and Higdon had been unraveling and that an enraged Higdon shot Freeman when he finally came home after ignoring her texts all day, and then refused to eat the dinner she had cooked for him.

 "She took the magazine out of the gun with the hands that had been preparing this food and was angry that he didn't want to eat it. She put bullets in that magazine. She put the magazine in the gun. She pulled the top of that gun back. She chambered a round into it, and she exerted five and three quarters pounds pressure on that trigger. And she pulled the trigger because she was angry." Lenhard told "48 Hours" the grease on the inside of the gun was evidence that the shooting of Steven Freeman was not an accident, but murder.

In an interview with Begnaud, Griffin police detective Adam Trammell used the same type of firearm Higdon used, a Glock 42, to show how to load the magazine and then pull back the slide to chamber a bullet.  Detective Trammel's on-camera demonstration illustrated investigators' theory of how that grease ended up on both the top of the gun, and more importantly, on the magazine inside the weapon.  

In his interview with "48 Hours," defense attorney Jorge Carabajal challenged the state's evidence: "They took a nice close-up picture of the gun. I didn't see that level of grease or anything on that gun other than maybe -- what you would have on your fingers. …" 

But the trial would be about much more than grease on a gun. Higdon testified that although she didn't know the gun was chambered, she had held the gun up that night because she was scared of Freeman. To the surprise of many in the courtroom, Higdon painted a picture of escalating abuse at the hands of Freeman. She read the jury multiple ugly, threatening text messages that Freeman sent to her a year prior to his death.  Higdon also testified that Freeman hit her, and on two occasions, that he raped her.

The prosecution was not buying it. In her cross-examination, Kate Lenhard confronted Higdon about never having complained about Steven's alleged abuse.

In the end, it was up to the jury to decide if the defendant was guilty of any of the charges against her. The verdict: not guilty.

Many in the court were stunned by the jury's decision to acquit Higdon of all charges: malice murder, felony murder, aggravated assault and possession of a firearm during the commission of a felony.

"48 Hours" spoke to some of the jurors to find out exactly what happened while they deliberated behind closed doors. Hear what they have to say on  "The Case Against Mary Katherine Higdon," now streaming on Paramount +.