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The couple who killed two Las Vegas police officers and the man who shot to death three Mounties in Canada don’t fit the ideology of right-wing extremism despite their anti-government rhetoric online, according to criminology experts.

Authorities in Las Vegas say Jerad and Amanda Miller gunned down the officers at a pizzeria, then left a Revolutionary War-era “Don’t Tread on Me” flag on the bodies along with a note reading, “The revolution is beginning” and a swastika meant to equate police with Nazis.

"That makes very little sense," said Dr. Jack Levin, a professor of criminology and sociology who is co-director of the Brudnick Center on Violence and Conflict at Northeastern University and has written extensively on mass murderers and serial killers.

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He said right-wing extremists typically focus their anger on federal authorities, not local law enforcement officers like these.

"They weren't the ATF, they weren't the FBI. They couldn't be seen as the representatives of a repressive government,” Levin told NBC News. "There are some militia group members who believe that the only valid authority is at the county sheriff level. In fact, many right-wing extremists love the police. They feel kinship to local law enforcement."

Dr. Michael Arntfield of Western University in Ontario also called the Las Vegas killings unusual — even beyond the rarity of an ambush aimed at police officers.

“I can never remember an attack in which an officer’s body is desecrated,” said Arntfield, a criminologist and professor who spent 16 years as a police officer and is the subject of the cold-case television show “To Catch a Killer” on the Oprah Winfrey Network in Canada.

Arntfield also sees similarities between the Vegas ambush and the attack on officers of the Royal Canadian Mounted Police in Moncton, New Brunswick, last week.

“Both of these sets of shooters were very prolific on social media over a short period of time,” he said in an interview.

And he said the short span between the attacks can’t be dismissed as coincidence.

“There is also strong evidence that mass shootings cluster in space and time based on what we call the learning theory of crime, and that most people in a pre-contemplative stage of offending (even fantasizing about offending) are often disinhibited upon seeing it done elsewhere,” he said in an earlier email.

“While Moncton and Vegas aren't near each other, I have little doubt that reportage of the Canadian killings had some bearing on the Vegas killings, right down to the motive,” he added.

Las Vegas Mourns Slain Police Officer

In Moncton, authorities say, officers responding to a call about a man with a gun wandering a neighborhood were ambushed June 4. Three were killed and two wounded. The gunman was captured less than 30 hours later. A Facebook page believed to be suspect Justin Bourque’s includes posts railing against the police and gun control and lamenting the supposed loss of personal freedom.

In Las Vegas, the couple shot the officers and a civilian who tried to stop them as they entered a Wal-Mart. During an ensuing gunfight, Jason Miller was killed by police and Amanda Miller shot herself, authorities said.

The Millers had traveled to Mesquite, Nevada, where rancher Cliven Bundy was in a standoff with federal agents over unpaid grazing fees. Hundreds of armed protesters gathered there after federal authorities began rounding up Bundy’s cattle. Eventually, the federal government backed off and released the cattle.

NBC station KRNV of Reno interviewed Jerad Miller at the protest in April and he said he felt sorry "for any federal agent that wants to come in here and push us around or anything like that.

"I really don't want violence toward them, but if they're gonna come bring violence to us, well, if that's the language they wanna speak, we'll learn it," he said.

Bundy’s son told the media that the Millers were kicked off the ranch because of their radicalism.

Levin said the reasons for being asked to leave may go beyond ideology. “You see less about politics than you do about psychopathology,” he said.

Despite the public anti-government views of the attackers in both cases, it would have been difficult for police to pick up on the threat for a variety of reasons, Arntfield said.

“It’s nearly to impossible to foresee or prepare for these kind of ambush attacks,” he said.

The primary reason is the disorganized and “lone wolf” nature of the attackers, who are untethered to a structured extremist organization that might be monitored, he said. Then there’s public resistance to police surveillance of social media — along with the sheer volume of posts, tweets and videos involved.

“You can’t possibly monitor even locally all of them, let alone external threats,” he said.

Arntfield said law enforcement agencies should focus on “intelligence-led policing” that depends on developing sources who are plugged into social media and will report suspicions about threats.

“Both these attacks will be interesting case studies for what the barometer is for determining what threats online are worth acting on,” he said.

And that’s not just an issue for the police.

He said that in some recent mass murder cases – such as the shooting of college students in Santa Barbara – people who saw threats on social media didn’t take them seriously, didn’t think the police would take them seriously or were too confused or frightened by them to bring them to authorities’ attention.

He said the police need to court the public’s help in identifying such threats.

He and Levin said changes in policing already underway have helped reduce the number of officers killed by criminals — from 74 in 1995 to 48 in 2012, according to the latest numbers from the FBI’s annual report on law enforcement deaths. That follows general downward trends in the murder rate and crime overall, Levin said.

“There’s a qualitative difference in the way the police relate to the local community. In many cities, community policing is the rule now,” he said. “They’re not seen as the army of occupation as they might have been 20 or 30 years ago.”

Still, Levin said, the sort of violence in Las Vegas points to a “much more general problem: Predicting dangerous behavior.”

“We like to think that we can predict family killers or workplace annihilators or cop killers. But we only see the warning signs after the fact,” he said. “We live in a country where we value personal freedom. We’re not going to turn our buildings into fortresses. We’re not going to put cameras in every place.”