DALLAS -- Tobias Mackey hadn't committed a crime, or done anything wrong, all he was doing was walking in a Dallas apartment complex in October of 2010.
Then, he came in contact with former Dallas police Officer Matthew Tate.
"When he did that shooting, I was standing two feet away from Tobias," said Sgt. Kenneth Chapin, who was standing next to Tate.
Sgt. Chapin told internal affairs investigators he was surprised by the gunfire.
"Initially, I was confused where the shots were coming from and drew my weapon because shots were being fired," he said.
Tate fired all nine shots, killing Mackey and shooting 11-year-old Xavion Collins in the arm.
Mackey's mother says her son was killed for no reason.
"I want the whole world to know my son did not die because he was trying to hurt somebody," Shelia Lewis said. "He was unarmed."
In court documents News 8 obtained, officers were at the complex to look for troublemakers. They talked about it on their squad car computers.
One message read, "Going straight to apts. or just grabbin people?"
The reply was, "Anyone that acts dumb or guilty."
Tate and Sgt. Chapin claimed when they saw Mackey, they yelled at him to put his hands up, but he wouldn't comply.
Tate said Mackey looked like he was reaching in his waistband for a weapon, so he shot him.
"I want the truth to be revealed to everyone, because right now, they are saying Tobias' shooting was a justifiable shooting," Lewis said.
Initially, three shots were fired. Witnesses say Mackey shouted "Why did you shoot me? I don't have anything!"
Officer Tate then fired more shots.
The Dallas Police Department, the Dallas County District Attorney’s office, and the local FBI cleared the officers. No charges were filed and no discipline was handed out.
So Shelia Lewis began a crusade for justice for her son.
"People don't know -- going up against the Dallas Police Department is not easy," she said.
Lewis sued, the city took a closer look at the case, and offered her hundreds of thousands of dollars, which she turned down. She then went to the U.S. Department of Justice and got them to open a civil rights case.
Three years later, Sgt. Chapin has changed part of his story.
News 8 has learned last month the Dallas Police Department reopened a criminal investigation and internal affairs investigation in the case. Chapin is now under investigation for lying.
And in recent depositions, Chapin told Lewis' attorneys there was no reason for Tate to shoot Tobias Mackey.
If the justice department gets a grand jury to indict Tate, it will be the first time ever a Dallas police officer will have been indicted in the shooting of an unarmed man.
"I am very hopeful," Lewis said. "I am very hopeful justice is here."
The Dallas Police Department and city attorney’s Office had no comment.