The capital murder trial for Terrance Black is under way in Collin County.
During opening arguments, prosecutors portrayed Black, 50, as a spurned lover who savagely killed his ex-girlfriend, 40-year-old Susan Loper.
Prosecutors allege Black's gun failed, so he beat her to death.
At one point, the judge angrily admonished Black at sidebar for turning and speaking to people in the gallery in court. The judge let him know in no uncertain terms if he did it again there would be a consequence.
Meanwhile, Black's defense team is attempting to shift focus to Jason Hays, a former boyfriend of Loper's that they said should have been investigated.
She also said that it was odd that on the day Loper went missing, everyone in her life, including her ex-husband Craig, Hays and other friends all showed up to lend support -- except Black.
Police said Loper was taken from the Gleneagles Country Club in Plano. Her body was found a day later in a field along the Dallas North Tollway in Frisco.
The first witness to take the stand was Loper's mother, Catherine Miller. She testified that Black lavished gifts on Loper and her son Jake, whether he was with her or not. Miller told police she thought Black was involved in her daughter's disappearance and that he seemed obsessed with her.
Plano police officer Joel Scott also testified today. He found Loper's body after getting information during a police briefing about the use of her car on the tollway. Scott was also one of the officers that arrived first at the scene at the Gleneagles County Club. He said he was familiar with the area where Loper's body was placed because he attends church an exit or so away from the area, at the Stonebriar Church in Frisco.
Jurors were also shown cell phone photos of bloody evidence, a bullet, footprints, and signs of a struggle at the pilates studio at the county club where Loper taught. The photos were taken by friends and clients of Loper, who said they initially thought the wind may have blown things around because a back door to the studio was open. As they further investigated the photos, they believed the photos were unusual as Loper's bag and a cup of coffee were on the floor.
The witnesses that took the photos said Loper was very neat at all times and that it was odd to see the room in disarray, even though Loper had planned to move from that location.
Black was arrested days later in Arizona after jumping 25-feet off the rim of the Grand Canyon while trying to elude park officials.
If convicted, Black faces an automatic life sentence without parole.
NBC 5's Frank Heinz, Greg Janda, and Randy McIlwain contributed to this report.