When they approached, Thomas ran, police said, and at one point, Thomas allegedly reached for a gun in his pocket.
His father says his son was shot in the back.
"They're lying, basically, saying that my son pulled a gun on them. But you can't pull a gun with your back turned from them and get shot 12 times in the back," he said.
Deputies said they recovered a weapon that was loaded.
They have not yet said what suspicions led them to Thomas in the first place, but say he was a gang member.
The deputy involved in the shooting is an eight-year veteran. He said there was no doubt in his mind that his life was in jeopardy when he saw the suspect reach for a weapon.
The investigation continues, and autopsy results are expected within days.
