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Convicted Boston Marathon Bomber Turns to Neuroscience Expert Witness in Sentencing Trial

As the sentencing trial for convicted Boston Marathon bomber Dzhokhar Tsarnaev continues, defense attorneys for Tsarnaev called respected neuroscience expert witness in an effort to avoid a death penalty judgment.  Consistent with the defense’s position during the early part of the trial, the expert has been called to provide testimony that minimizes Dzhokhar’s role in planning and executing the attacks.

Prosecutors Point to Unrepentant Behavior

As the sentencing phase of Dzhokhar Tsarnaev’s trial began, prosecutors attempted to paint the defendant as an unrepentant and willing participant in the Boston Marathon bombing attack.  Tsarnaev was convicted last month on all criminal charges levied against him, including charges of terrorism and conspiracy to deploy weapons of mass destruction against the public.  Prosecutors have alleged throughout the trial that Tsarnaev was equally responsible for the planning and execution of the attacks along with his brother, Tamerlan.

Beyond the evidence used to convict Tsarnaev of the crime, prosecutors have used his recent behavior to show that he remains defiant and without remorse for his actions.  Dzhokhar is responsible for writing a series of notes that prosecutors argue demonstrate his willingness to engage in acts of Islamic terrorism, and was recently photographed flipping a jail cell camera off in anger.  Prosecutors have pointed to the defendant’s activities before, during, and after his trial as signs that he was not unwillingly convinced to take part in the attack by his brother, but instead was an accomplice and equal partner to the crime.

Defense attorneys for Tsarnaev have countered prosecutors by building upon the strategy they employed during trial and calling a neuroscience expert witness to testify that the defendant’s brain was too immature during the planning and execution of the attacks to make him sufficiently culpable as to warrant the death penalty.

Tsarnaev’s Brain Development at Issue in Sentencing

Dr. Jay Giedd, chief of brain imaging at the Child Psychiatry Branch of the National Institute of Mental Health took the stand last week to testify that Dzhokhar’s brain was not fully developed at the time of the attacks.  According to Dr. Giedd, Dzhokhar, who was 19 at the time of the bombing, did not have a fully developed prefrontal cortex, which is the area of the brain responsible for planning, impulse control, and judgment.  Neuroscience research indicates that the prefrontal cortex is not fully developed until the late twenties, and as a result, the defendant’s capacity to control aggression or excitement was weak leaving him vulnerable to suggestive influence.

Dr. Giedd told jurors that teens with underdeveloped prefrontal cortex are unable to adequately process risk vs benefit analysis, and are more likely to accept actions that favor short term rewards with little consideration of long term consequences.  Although Dr. Giedd conceded on cross-examination that some brains develop faster than others, and Dzhokhar had the capacity to comprehend the consequences of his actions, his testimony supported the defense’s case that the defendant was developmentally immature and vulnerable to his brother’s influence.

Use of Brain Development Expert Witnesses Growing

The immature brain strategy employed by using Dr. Giedd as a neuroscience expert witness is not uncommon as defense attorneys across the country have incorporated brain development into serious offense trials.  Advances in neuroscience provide opportunity for neuro expert witnesses to inform jurors about potential brain development issues or defects that can influence judgment, decision-making, and ultimately behavior.  As in the Dzhokhar Tsarnaev case, neuro expert testimony is not always used to exonerate the defendant, but is deployed in an effort to reduce sentencing.

In this case, Tsarnaev’s legal team turned to Dr. Giedd’s expert testimony to lend scientific credence to the point they have hammered home since the high-profile trial began: Dzhokhar committed the crimes of which he was accused, but he lacked the necessary desire and intent to plan and execute a terrorist attack without the influence of his older brother.  Considering Dzhokhar’s brain development and the influence his older brother had over him, defense attorneys have argued that life in prison is the more appropriate sentence rather than death.