Thousand Oaks shooting: What led Ian David Long to commit mass murder?

THOUSAND OAKS, Calif. (KGO) -- A sequential model two American professors came up with to help us understand mass shootings at schools may provide insight into the deadly attack on a popular bar in Thousand Oaks.

Ian David Long, 28, has been identified as the suspected gunman in the mass shooting at Borderline Bar & Grill.

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The shooting happened late Wednesday inside Borderline Bar & Grill. At least a dozen people were killed, including a sheriff's sergeant, Ron Helus. None of the other victims have been identified.

Police are still searching for a motive. What lead Long to commit mass murder?

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General strain theory dates back to the 1930's and was further developed in the 1990s by Robert Agnew - to understand what types of societal "strains" or "stressors" which lead to criminal behavior.

In 2009, two American professors, Eric Madfis and Jack Levin, came up with a sequential model to understand mass shootings at schools.

Although the Borderline Bar & Grill shooting was not on a school campus, it was a place frequented by college students. The Madfis & Levin model may provide insight.

The Madfis & Levin model suggests a shooter goes through five stages before committing a mass murder.

1. Chronic strain

2. Uncontrolled strain

3. Acute strain

4. The planning phase

5. The attack

Chronic strain refers to repeated trauma - bullying, isolation etc. In David Long's case what led up to his PTSD may fall in this category.

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Uncontrolled strain is when an individual starts to exhibit delinquent behavior - in Long's case we've heard of reports of police being called to his home multiple times.

Acute strain is "the straw that breaks the camel's back." It's usually a specific event involving real or perceived rejection in some way. The event triggers the would-be shooter to start the planning phase.

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The planning phase can vary in length from a few hours to years.

Then, the attack phase: where the person actually carries out an attack, usually in a place where they will have a high casualty count like a school or bar. This is where firearms expertise can play a factor; the person must actually be able to use the weapons they choose.

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So, as we start to get more background information on David Long from the Thousand Oaks shootings - you may start to see some facts fit into this model.

To be clear, experts agree that there's no real profile for a mass shooter, but models like those developed by Levin & Madfis help to understand the journey these troubled individuals go through before committing an atrocity.

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