It took jurors around three hours to find a Jefferson City man guilty of first-degree murder and armed criminal action, for killing his wife at a Jefferson City McDonald's in December 2010.
Keith Kellner, 49, showed no emotion as the verdict was read just after 5 p.m. Tuesday afternoon.
By state law, the first-degree murder conviction means Kellner will spend the rest of his life prison, without parole, for killing of his wife Pam, 44.
Cole County Presiding Circuit Judge Pat Joyce will hold a formal sentencing hearing later, then Kellner will begin his sentence in the state prison system.
Before closing arguments were made Tuesday afternoon, Joyce went over the jury's instructions, including the other possible charges the jury could find Kellner guilty of - including second-degree murder, voluntary manslaughter and involuntary manslaughter.
In closing arguments, Assistant Cole County Prosecutor Anji Gandhi urged jurors to go back to earlier testimony from Keith Kellner's co-workers and family, which she said showed "he couldn't stand his wife to be out of his sight and that he would kill her if she left him."
Gandhi added: "You'll also recall his thought was, "If I kill myself then she'll come back to me.'
"This is not a sad man. There is plenty of evidence that this was premeditated because he texted her numerous times what he would do to her - and he did it."
Gandhi also urged jurors to remember testimony from a Missouri Highway Patrol Crime Lab firearms expert, that it took up to 10 pounds of force to pull the trigger and fire the gun that was used in the crime - which goes against Keith's defense that the gun went off easily after he accidentally hit it on the table of the restaurant booth where he and Pam were sitting.
But Keith's attorney, Public Defender Jan King, told jurors most of what they had heard was not real evidence.
He said while Keith did shoot and kill his wife, the crime did not reach the level of first-degree murder.
"Love is an irrational emotion that makes people do incredibly stupid things sometimes," King said. "It does not speak to the kind of homicide this is.
"My client was a klutz and it's a wonder he didn't shoot himself getting the gun out of his pocket."
King argued that the crime fit the charge of voluntary manslaughter, due to the reckless action involved in this crime, not the cool reflection called for under first-degree murder.
However, Gandhi argued that King failed to add that, while first-degree murder calls for a person to have acted with cool reflection, that also means for any length of time, no matter how brief.
In often emotional testimony, Keith took the stand to talk about what led up to the night Pam was killed.
In previous testimony, texts taken from Keith and Pam's cell phones were shown to the jury, indicating that Keith wanted to know where Pam was at all times - and was upset when he found out she had left their home and had started seeing another man.
King asked Keith if the number and type of texts he sent were accurate and Keith said yes.
"I was hurt," Keith said.
The day of the killing, Keith talked about how he was upset that he hadn't been able to spend a break-time with Pam at their Revenue department office, and that she had been allowed to go home and he had not.
He said he stayed until it was time for him to go home at 4 p.m., then - after driving around for a time - went to his second job with a cleaning company, around 4:45 p.m.
He testified he left that job around 7:45 p.m.
Keith said he tried to get ahold of Pam and then went to his house where he contemplated killing himself.
He said he got a gun out of a desk drawer and started to put it to his head, but then decided he wanted to see Pam and knew she was working at McDonald's on Jefferson Street.
He took the gun with him in his coat pocket - and his hand on the trigger - when he went into the restaurant.
Keith told King he didn't know if the safety on the gun was on or off.
Eventually he and Pam went to a booth to talk.
"I asked her to please come home, but she said she wasn't," Keith cried. "I pulled the gun out, closed my eyes, hit the table and the gun went off - hitting Pam."
Keith said he was shocked and didn't know what was going on after the gun went off so he ran out the door, but looked to see Pam get up and say "Oh my God."
Under cross-examination from Gandhi, Keith said he was not angry, but hurt that his wife didn't want to come back home.
He also admitted he did follow her around the city the night before the shooting, trying to find out where she was staying, but said he was not stalking her.
"I just wanted to have her come home," he said.