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Drug crimes in eastern Montana have more than doubled. Assaults in Dickinson, N.D., have increased fivefold in just two years. And the once-sleepy town of Plentywood, Mont., has seen three assaults with weapons in the past few months — a prospect previously unheard of in the tiny community tucked against the Canada border.

Booming oil production has brought tens of thousands of jobs and hundreds of millions of dollars in new revenues to communities across a wide expanse of the Northern Plains. But it also has brought more crime, forcing law enforcement from the U.S. and Canada to deal with spiking offenses ranging from drug trafficking and gun crimes to prostitution.

The rural region is emerging as one of the top oil producing areas of North America. Officials say up to 30,000 more workers could descend on the Bakken oil fields of Montana, North Dakota and Saskatchewan in the next few years.

The recent kidnapping and brutal murder of Montana teacher Sherry Arnold tragically underscored the changes brought on by the rapid pace of drilling. Two men are in custody, but the case has left residents shaken and led to a huge rise in applications to carry concealed weapons in Montana and North Dakota.

In the wake of Arnold's killing in the town of Sidney, which is quickly being overtaken by the boom, federal prosecutors began a two-day retreat Monday in Glasgow for about 150 police, sheriffs, federal agents and other law enforcement to craft a common strategy to deal with rising crime.

Towns like Plentywood, population 1,600, were until recently places "you could send your kids to the pool in the summertime on their bikes and not have to worry about it," said Sheridan County Attorney Steven Howard.

"All those things are changing," he said, adding that the Arnold case "has had a chilling effect on our people."

Monday's conference already was being planned before Arnold's death, said Michael Cotter, the U.S. attorney for Montana. But Cotter said the killing illustrated the importance of close coordination among law enforcement as officials gird for more crime.

Government officials predict the boom could last another decade or more as companies tap into a reserve estimated by the U.S. Geological Survey to hold more than 4 billion barrels of crude. Oil company executives say there's even more, upwards of 20 billion barrels that will be extracted using drilling techniques that were only recently perfected.

Towns like Dickinson already have seen the negative spinoff effects from workers hoping to cash in on the boom. For many agricultural communities, including Plentywood, officials say the changes have just begun.

The situation is exacerbated by a housing shortage that is spurring the construction of sprawling "man camps" that can accommodate hundreds of out-of-state oil workers.

The suspects in Arnold's killing — 48-year-old Lester Van Waters and 22-year-old Michael Spell — allegedly traveled to the Bakken from Colorado in search of jobs in the oil patch. Court records suggest Spell and Waters had been smoking crack cocaine and were living out of Waters' vehicle when they snatched Arnold off a Sidney street in the pre-dawn hours of Jan. 7.

Industry representatives say companies go to lengths to ensure the workers they hire won't cause trouble — either on the job or in the community.

Drug tests and background checks are standard for many companies, said Kari Cutting with North Dakota Petroleum Council. She added the lack of housing can quickly deter would-be workers who show up without a position already secured.

Cutting noted that neither Spell nor Waters was employed by the oil industry, and the two had been in the region only a short time before the alleged crime.

"We do know there are challenges," she said. "Any opportunity has challenges that need to be overcome, and we want to be part of the solution in all this."

Some law enforcement officials, including Valley County Sheriff Glen Meier, said the increase in crime has roughly tracked the increase in population, meaning the actual rate of offenses has been little changed.

"You have to put it into perspective. Ninety-nine percent of the people (working the oil fields) will be an asset to the community," he said.

Yet there are indications that communities and several Indian reservations in the Northern Plains have found themselves dealing with new types of crime more commonly associated with urban areas. Organized drug trafficking and prostitution rings top the list, officials said.

Mercer Armstrong with the Royal Canadian Mounted Police said the areas of southern Canada within the Bakken have seen a "major influx of criminality." That includes organized criminal enterprises from British Columbia moving into rural areas to establish the drug trade, he said.

The Bakken-area communities aren't the first to suffer the downsides of a boom, and Utah State University sociologist Richard Krannich said lessons can be drawn from other parts of the country where energy industry workers have come and gone.

"After the 'surprise' of rapid growth during the initial few years, most areas seemed to be reasonably successful in catching up," Krannich said.

In the U.S., federal agencies including the FBI and Bureau of Alcohol, Tobacco, Firearms and Explosives are addressing the problems in the Bakken by adding new agents and trying to share intelligence with state and local officials.

Montana and North Dakota also have more state troopers on the road, in part to address rising numbers of traffic offenses including driving while intoxicated.

Some law enforcement agencies are having trouble filling posts. Qualified applicants will pass over deputy positions that start at less than $20 an hour to take oil field jobs that pay two to three times as much.

The result, said Tim Purdon, the U.S. attorney for North Dakota, is that police are in "100 percent reactive mode, running from call to call."

"Local departments have been squeezed to the point where they're having trouble performing proactive police works. We don't have the time," he said.