Attorneys hope testimony over brain development could remove death penalty option

Efrain Diaz, Justin D. Smith and a 17-year-old have been charged with fatally shooting...
Efrain Diaz, Justin D. Smith and a 17-year-old have been charged with fatally shooting Jonathan Krueger, a junior at the University of Kentucky, on April 17.(WKYT)
Published: Jul. 17, 2017 at 11:58 AM EDT
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A hearing on Monday in a high-profile murder case in Lexington centered around scientific research on brains. The defense team in the case is hoping that research may lead to the judge taking the death penalty off the table for their clients.

Defendant Efrain Diaz was 20-years-old back in 2015 when Lexington Police arrested him for the slaying of 22-year-old Jonathan Krueger. Justin Smith was 18-years-old. Police also charged him with the robbery and murder that claimed the UK student's life.

A prior federal ruling takes the death penalty off the table for defendants who commit a crime at age 17 or younger. While both men were older than that at the time of their arrests, their

attorneys brought in a psychology professor and expert in hopes of proving that their brains were still in an immature state.

Ph.D. Laurence Steinberg, a psychologist at Temple University, says brains of 18- and 20-year-olds typically function more like young teens than adults. However, Dr. Steinberg said there is no way to evaluate brain maturity on an individual level.

"Even though adolescence is a time of relatively more risky behavior, that manifests itself in different ways in different people," Steinberg testified.

That professor is set to send the court additional research to back his testimony.

A third suspect charged in the murder, Roman Gonzalez, was 17 at the time of the crime. He will not face the death penalty when his case goes to trial.