Trying to understand why some people commit murder might seem like an impossible task. But a new study appears to show how thinking about murder turns into action.

Dr. Matthew DeLisi, a professor of sociology and criminal justice at Iowa State, and his team analyzed the minds of 863 criminal offenders to determine the relationship between homicidal thoughts and fantasies and actually committing murder. He believes their findings could drastically change the way we currently sentence offenders in the U.S., and potentially help reduce crime.

"I've always studied more severe offenders, and homicide is certainly on that list," DeLisi told Seeker. "I'm aware of HI (homicidal ideation) from my interests in psychiatry, but was surprised how criminology has overlooked this important topic."

As many as 79 percent of men and 58 percent of women report experiencing at least one homicidal thought at some point in their life. The risk of transitioning from thought to action, DeLisi said, increases when a person begins to think about situations where homicide might be appropriate, or if they begin simulating the act of killing someone.

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When most people have a homicidal thought, it happens in a flash during an argument, but then they quickly move on. For someone in prison, however, these thoughts are part of their everyday emotions. Their anger, hostility and aggression are heightened within the environment of a correctional facility, so they may be more likely to contemplate murder.

This is one of the reasons offenders made a good test population for DeLisi's study.

Of the offenders surveyed, only 12 percent exhibited evidence of homicidal thoughts. While that's a relatively small number, DeLisi says it's a reliable indicator of criminal behavior.

The group who experienced murderous thoughts had committed more severe crimes including kidnapping, assault and armed robbery, in addition to homicide. They had nearly three dozen arrest charges and 20 convictions each, they repeatedly violated probation, and most had committed their first crime by age 14. He also found that most prisoners with homicide convictions had been experiencing homicidal thoughts from a young age.

Offenders who did not experience murderous thoughts had committed significantly less severe crimes.

The majority of correctional clients analyzed in DeLisi's study were of the same race, gender and were convicted of the same crime: white men guilty of methamphetamine distribution. The research team also controlled for several mental disorders to ensure that homicidal ideation was the sole explanation for the offenders' crimes.

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DeLisi said that homicidal thoughts are not classified as a mental illness but those who frequently think of murder aren't healthy either.

The ultimate goal of the study was to identify offenders who experience, or have experienced, homicidal thoughts in order to reduce their threat to the public.

"The practical import of [our] findings is to more closely supervise offenders who [reveal homicidal thoughts]," DeLisi said. He suggests that probation officers could assign additional treatment for these individuals, and their cases could be assigned to senior officers, as well as mental health specialists, to ensure they are properly handled.

Studying homicidal thoughts could prove useful in understanding and preventing crime in other settings of violence as well. "Individuals living in high violence areas become desensitized to violence, and homicide also takes on a protective function," DeLisi said.

Researching people with homicidal thoughts in high-violence areas could provide insight into when and where violent acts will occur within a city, allowing law enforcement to take more preventative measures, DeLisi said.

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