At the time, Wilson was an employee at the store located on Cherry Valley Road.
Prosecutors say Wilson had gone to the store the morning of the shooting, left and then returned. They say "his only intention was to kill."
The prosecution told the court that Wilson went straight to the second-floor office and killed Ray Wishropp, who was the manager of the store. They say Wilson also tried to kill four others.
Wishropp was a father of seven and a new grandfather when he was killed.
"Someone took him away, tried to destroy this family," said Ray Wishropp's father, Rupert Wishropp. "But I believe in the justice system and we will get justice."
A 911 call was played in court Monday and police medics who were at the scene also testified.
The prosecution also plans on calling the four survivors of the attack to the stand.
Wilson has pleaded not guilty to charges of second-degree murder and attempted murder.
His lawyer said in his opening statements to the jury, "Be fair determining what was in his head when he fired that gun."
If convicted, Wilson faces 25 years to life in prison.