There's not much detail in the linked article and I don't know anything about the testimony, but for the sake of argument let's assume that:
- Carmack-Belton came in and stole something.
- Chow caught and confronted him.
- Carmack-Belton responded by pointing a pistol at Chow and his son, and threatened to kill them.
- Carmack-Belton then ran from the store and continued to run away.
- While Carmack-Belton was still running away, Chow chased and shot him.
This is absolutely an unlawful shooting. When Carmack-Belton pulled the gun Chow had justification to use deadly force against him, but at the moment Carmack-Belton began to run away that justification vanished. Chow is clearly liable for some kind of murder charge, and absent some significant mitigating circumstances I don't see how a reasonable jury would acquit him.