The teenager accused of killing a Clayton County sheriff's deputy  testified in court Thursday afternoon in his defense.  Prosecutors say Jonathan Bun shot and killed Deputy Rick Daly during a traffic stop last July.

In the third day of Bun's trial, prosecutors showed a video of the teen's first interview with authorities following the shooting.

"I thought with my hands not with my head," said Bun.

Ioana Enerich with the GBI forensics lab testified Wednesday "it's with a reasonable scientific certainty" that DNA on a handgun matches Jonathan Bun or an identical sibling, who would have identical DNA.

Other authorities who were at the scene also testified on Wednesday.

"I could see blood on [Daly]," said Fayette County Sheriff's Deputy Chris Robinson, "and the first that popped in my mind is, 'Oh, my God. He's been shot.'"

Bun was 17 when he was accused of shooting Daly twice.  The veteran deputy was killed while trying to serve an arrest warrant on an armed robbery charge. 

Bun, now 18, is charged with several charges including malice murder and felony murder.  He faces life in prison without the possibility of parole.

Closing arguments are set to get underway on Friday.