TAMPA - Spencer Arthur put his head down as the jury heard the 911 call he made on September 26, 2010.
"I see the blood, I saw the gun, heard it go off," Arthur told a dispatcher.
Arthur was skateboarding on the basketball court at the Twin Lakes subdivision in Valrico.
David James was there too, playing basketball with his 8-year-old daughter..
Spencer testified that James came to his defense when neighbor Trevor Dooley angrily yelled that skateboarding wasn't allowed.
"When someone has authority, you know you should listen to them. So I stopped skateboarding," said Arthur.
The prosecution says Dooley, 71, pulled out a gun as he and the Air Force veteran argued.
That argument got physical. And prosecutors say James tried to get the weapon away from Dooley.
"They are struggling over the firearm and they fall down and the defendant pulls the trigger and shoots and kills David James," said prosecutor Lori Ellingsworth.
Dooley's attorney says it was self defense. That James, who was twice his size, tossed the part time school bus driver to the ground and started choking him.
"He's dying, he's taking his breath away from him, he feels he's going to die. He fires the gun in one shot," said defense attorney Ron Tulin.
Spencer testified he didn't see how the two ended up struggling on the ground and he did not see Dooley shoot.
And on that 911 call he seemed to blame himself for the deadly argument that started over his skateboarding, telling the dispatcher, "it's my fault."
We are also expecting to hear testimony from James daughter. She'll be called for the defense.
Dooley is also expected to take the stand. He faces up to 30 years if convicted on all the charges.