ATLANTA (AP) - The number of justifiable homicides in Georgia has increased since 2006, the same year state lawmakers passed a version of the controversial self-defense law that's the target of national scrutiny in the wake of the Trayvon Martin shooting in Florida.

An Associated Press analysis of Georgia Bureau of Investigation data found that justifiable homicides involving private citizens averaged seven per year in the three years before the so-called stand your ground law took effect. It then jumped to an average of 13 per year in the five full years since then.

Killings that involved police officers also saw a similar increase. Meanwhile, Georgia's overall murder rate has decreased between 2000 and 2010, from a rate of 6.1 per 100,000 people in 2000 to 5.4 per 100,000 in 2010. Georgia's population has increased 20 percent during that time.

Prosecutors and criminologists aren't certain why the number of justifiable homicides has jumped, but several were reluctant to tie the increase to the stand your ground statute. The law gives people wider latitude to use deadly force rather than retreat under threat of death or serious injury.

"That's surprising," said Gwinnett County District Attorney Danny Porter, who suggested the rise could be linked to an overall willingness by the public to use their guns if they perceive a threat.

Georgia's law is in the spotlight after a similar statute in Florida was initially cited as the reason not to charge neighborhood watch captain George Zimmerman with killing Martin, who was 17 and unarmed at the time of the shooting. Zimmerman, who has claimed self-defense, has since been charged with second-degree murder.

Willene White-Smith, a manager at Georgia's Crime Information Center, the state agency that collects Georgia's crime data, said the increase could be a result of improved reporting because investigators have better training on when and how to classify a killing as a justifiable homicide.

Between 2003 and 2005 there were 21 justifiable homicides involving private citizens, or seven a year. The numbers jumped between 2007 and 2011, when there were 65 justifiable homicides involving private citizens, an average of 13 a year.

The calculations don't include figures from 2006 because the stand your ground law took effect halfway through the year. They also do not include early and incomplete figures from 2012.

Justifiable homicides are killings in which authorities, prosecutors or a judge can decide no crime has been committed after reviewing the facts of the case. Under Georgia's law, defendants who are charged with a crime can ask a judge to grant them immunity if they believe the killing is in self-defense long before a trial begins.

Those who are charged with murder often claim they acted in self-defense, so prosecutors and investigators tend to scrutinize each killing on a case-by-case basis.

"I don't sense that the statute has led to a greater change," said Tim Vaughn, the Oconee County District Attorney. "You just have to apply commonsense when evaluating the facts of each situation, and ask what a reasonable person would do in each particular situation. And I don't think that it's been a drastic change if you just apply that rationale."

The fatal shooting of Canard Arnold in December forced Fulton County prosecutors to view his death through a similar prism.

Arnold was killed by security guard Christopher Hambrick after police say the guard stumbled upon a gunfight between the teenager and another person near the apartment complex where he was working. Arnold's family said the teen didn't confront or threaten Hambrick and was running away from another fight, but the guard said the shooting was justified.

Fulton County District Attorney Paul Howard came to the same conclusion, finding that Hambrick fired because he was being shot at. He noted that Arnold died with a weapon inches from his hand, indicating that the teenager was likely armed at the time.

Arnold's family, meanwhile, is planning to file a wrongful death lawsuit against Hambrick and the security company where he works, and family attorney Christopher Chestnut called Hambrick a "rogue vigilante" who tracked down Arnold like he was his prey.

Some prosecutors say Georgia's law could encourage poor decisions, echoing a nationwide debate that was sparked by Martin's death in Florida.

"I don't have a problem with stand your ground when it's used properly," said Ken Hodges, a former Dougherty County prosecutor. "You shouldn't seek out trouble. But conversely I don't feel like you should have to retreat if harm may come to you."

In many instances the data doesn't contain enough information about what led to a particular killing.

Sometimes, such as the December 2010 shooting death of 30-year-old Yuhanna Williams, the self-defense claims are relatively clear-cut.

Williams was holding a knife to Ryan Moore's throat while trying to rob him at a Conyers grocery store when Moore grabbed his gun from his holster and shot Williams in the face. Investigators said Williams was still clutching the knife when they discovered his body, and Moore told them he was defending himself. Witnesses corroborated his story and authorities quickly found the killing to be justified.

Other cases involving self-defense claims are far more complicated.

John McNeil said he had little choice but to open fire when Brian Epp charged at him with a knife during a December 2005 shouting match in Cobb County. But the victim's knife was found in his pocket after the shooting, and prosecutors decided to charge McNeil with murder. He was convicted and sentenced to life in prison, a decision the Georgia Supreme Court later affirmed in a 6-1 ruling.

The lone dissent came from then-Justice Leah Ward Sears, who argued prosecutors failed to prove McNeil wasn't defending himself. The NAACP and other groups have called on prosecutors to review the case.

Cobb County District Attorney Pat Head, though, stands by the decision to charge McNeil. He said the case is a reminder of the potential pitfalls of self-defense arguments.

"Just because someone hits you in the face doesn't mean you pull a .45 and shoot him in the head," he said. "It can be hard to prove it's self-defense because the jury puts themselves in the same footing as anybody else."