(KCBS) – A new study finds there’s no measurable increase in crime when a marijuana dispensary opens. What’s more, when a dispensary is forced to close, there’s an immediate increase in crime.

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It’s a pattern researchers had already discovered with the opening and closing of restaurants.

So where did this notion of increased crime originate?

“I think it’s supported by a lot of people who don’t want dispensaries in their neighborhoods. And it’s certainly been promoted by a lot of law enforcement,” said Mireille Jacobson, an associate professor of Economics and Public Policy at UC Irvine and the study’s coauthor.

Jacobson’s curiosity was sparked when she saw the pattern play our in her own community of Venice Beach when pot dispensaries there were forced to close.

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She believes an old theory called “eyes on the street” may be responsible.

“You have kind of an informal policing when there are businesses that are open, just from people coming in and out, people that are in the restaurants or dispensaries. And that when you shut them down, you lose some of that,” Jacobson told KCBS.

Guards at dispensary doors may help, but that doesn’t explain the whole story.

“We find such a similar pattern of results for restaurants, and they usually don’t have guards at the door,” Jacobson said.

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The study is published in the Journal of Urban Economics.