Atlanta Police Detective Arthur Bruce Tesler presented himself as a rookie narcotics officer but even he lied like a pro, prosecutors said.

Assistant District Attorney Kellie Hill made that point to a Fulton County jury this morning before it was to start deciding Tesler's fate for his role in the killing of a 92-year-old woman.

"Mrs. Johnston is dead because of a lie," Hill said. "No, he didn't pull the trigger."

In a case where the jury has to decide whether it believes Tesler's testimony that he didn't know a search warrant was illegal and later he felt forced to participate in the cover up, Hill reminded the jury he lied to the FBI.

She also made it when Tesler was on the witness stand Wednesday when she asked about his recorded statement in an FBI investigation of Kathryn Johnston's death.

"You heard your voice when you were lying to the FBI," Hill said. "Is there anything about your voice that would have let Agent [Joe] Robuck know that you were lying?"

"I don't believe so," Tesler responded.

"So tell me, how am I supposed to know when you're telling the truth?" Hill asked.

Tesler, 42, is the only officer to face a jury regarding his actions on Nov. 21, 2006, when his narcotics team conducted a raid at 933 Neal Street and killed Kathryn Johnston. The team had been told a drug dealer named "Sam" operated from the house and had a kilo of cocaine but it lied to a judge by saying it verified its informant's information. The team was fired on by the elderly Johnston when knocking down her door.

The Fulton Superior Court jury is to start deliberating this afternoon on whether Tesler is guilty of violating his oath of office, lying in an official investigation and false imprisonment for surrounding the Johnston house during an illegal search.

Tesler, who had been a narcotics detective for a short time, told the jury that his former partners Gregg Junnier and Jason "J.R." Smith planned the cover up of the wrongdoing that led to Johnston's death. He said they routinely took shortcuts around the law to get warrants in order to make arrest quotas.

Defense lawyer William McKenney argued that the real culprits were Tesler's more experienced partners, Junnier and Smith, who had faced murder charges and have pleaded guilty to voluntary manslaughter.

"This is a tragedy, that is certain," McKenney said.

"One tragedy happened by mistake.... Don't ruin this officer, don't ruin his family.

"I think what we have to consider is what this unit was all about before Arthur Tesler got there."

McKenney reminded jurors of testimony that described rampant lying for warrants in the narcotics unit, where drugs were planted in residences when raids didn't turn up any and on suspects to extort information. He noted that the entire culture of the police department encouraged the lying by setting near impossible quotas that officers had to meet for drugs or search warrants.

Hill said such arguments were a distraction.

Mr. McKenney said you have to consider his client's frame of mind, that the department was corrupt from the top down," Hill said. "Well he (Tesler) chose to be part of that corruption."