PHOENIX - Is James Peters one trigger-happy cop? Or just an aggressive police officer who happens to find himself in more than the usual number of explosive situations?

Those are the questions police in Scottsdale are fielding after Peters was involved in his sixth deadly shooting over the past decade in the sprawling Phoenix suburb of almost 220,000 people.

All five previous killings were ruled justifiable by local prosecutors, as was a shooting in which the victim survived, and one of them even earned Peters a medal.

But after the latest killing - a particularly shocking one, involving a man cut down by a single rifle shot to the head Tuesday while clutching his baby grandson - authorities are again scrutinizing the 12-year police veteran's record.

"It's not a normal amount of officer-involved shootings. It's an anomaly in our department and in most departments," said Sgt. Mark Clark, a spokesman for the 435-officer force.

Police declined to make Peters available for an interview, saying policy prohibits him from talking to the media.

With its year-round sunshine, Scottsdale has become a magnet for professionals, retirees and winter tourists, and is known for its fine resorts, golf courses and expensive second homes. It is considered one of the safest cities in metropolitan Phoenix. But it also has a grittier side, and the latest shooting happened in the working-class south end of the city.

Peters was among six officers called to the home of John Loxas after a neighbor told a 911 operator he was holding his 9-month-old grandson and threatening them with a gun. Peters and five other officers were getting ready to go into the run-down, trash-strewn home and get the baby when Loxas opened the front door, still holding the child, and refused to come out, police said.

Peters fired his scope-equipped police rifle as Loxas leaned over and reached back into the house, authorities said. Loxas, 50, died instantly. The baby was not hurt.

The police department defended Peters, saying he was trying to save the baby's life. Police said that while Loxas didn't have a gun when he was shot, the loaded handgun they believe he had been brandishing earlier was found tucked into a couch just feet away and a loaded shotgun was also discovered nearby.

A list compiled by The Arizona Republic that police said was accurate shows Peters' first shooting was in 2002, when he was one of three SWAT officers who wounded a man during a standoff in a domestic violence case. Between 2003 and 2010, he was involved in five fatal shootings. In some of those cases, he acted alone; in others, fellow officers also fired.

The Maricopa County Attorney's Office investigated those shootings and ruled them justifiable, Police Chief Alan Rodbell said. In one instance, Peters received the department's medal of valor for killing a man who was holding a grocery store clerk hostage at gunpoint.

In 2010, police stepped back and did a review of all of the shootings and tried to determine if there was something they had in common.

"There was nothing that indicated there was any sort of issue with his training or assignments that would be causing this," Clark said. "You take each individual case, and his reaction was within policy and as expected for each officer, for any officer put in the exact same situation."

This time, the department will examine the same questions again, in an investigation the chief said will probably take weeks. The findings will be turned over to the county attorney.

Mike Rains, a suburban San Francisco lawyer who represented officers involved in hundreds of shootings in the past 30 years, said that any officer with so many shootings deserves extra scrutiny.

"Seven shootings is a hell of a lot," Rains said, arguing that Peters is either very aggressive in taking calls that end up requiring him to shoot or he is quicker on the trigger than he should be.

Maria Haberfeld, a professor at the John Jay College of Criminal Justice in New York City, said the four shootings that he took part in as a member of the SWAT team should be taken out of the equation, since SWAT officers are the ones most likely to use deadly force.

But the three remaining shootings are still higher than normal, since the average police officer might pull out his gun just a couple of times in a career, Haberfeld said.

"Because of his background in SWAT, he would have a predisposition maybe, maybe, to use his gun in a more assertive manner than his colleagues," she said. But she noted that the shootings were ruled justified, which suggests "a picture of somebody who is a true professional. So I don't see so much the concern that the public should have or the department should have."