(NEW HAVEN, Conn.) -- A "perfect storm" of drug abuse, childhood sexual abuse and head injuries were at the root of Joshua Komisarjevsky's "poor decision-making" the night he and an accomplice invaded the home of a Connecticut doctor, beat him and killed his family, according to a neuropsychologist testifying in Komisarjevsky's defense.
The accomplice, Steven Hayes, was tried and sentenced to death for his role in the deadly home invasion and is currently serving his sentence on Connecticut's death row. Komisarjevsky's legal team is attempting to spare their client the same fate for what many believe is the most horrific crime in Connecticut's history.
On July 23, 2007, according to prosecutors, the two men broke into Dr. William Petit's house in Cheshire, Conn. During the home invasion, they beat Petit about the head with a baseball bat and tied him up. Hayes raped and strangled Petit's wife, Jennifer Hawke-Petit, 48. Their two daughters, Hayley, 17 and Michaela, 11 were tied to their beds for hours and terrorized.
Komisarjevsky has admitted to sexually molesting Michaela. The two men then poured gasoline throughout the house and set it on fire.
Komisarjevsky's lawyers argue that Hayes was responsible for buying and pouring the gasoline and setting the house on fire. On Thursday, for the second day in a row, Dr. Leo Shea discussed a neuropsychological evaluation he performed on Komisarjevsky. The interviews took place on a series of dates in 2010.
In the evaluation, which has been publicly released, Komisarjevsky told Shea that he had been sexually abused by a foster child his parents took in to their home. Komisarjevsky said he had been raped orally and anally and burned with cigarettes by a 15-year-old boy.
Komisarjevsky's parents attempted to get him help through their church, according to the report, which says the parents "got the elders, to put their hands on me, to cast out sin, to heal me. I was so scared and felt smothered." Komisarjevsky also told the doctor that he started self-mutilation when he was 13.
Komisarjevksy also sustained five concussions at a young age -- one of which occurred on Jan. 20, 1990, when his head hit the windshield of the family car.
That accident was so traumatic, according to the report, that Komisarjevky's personality changed and he became "more agitated, frustrated."
Shea performed a number of cognitive tests on Komisarjevsky and summed up his 15-page evaluations this way: "Mr. Komisarjevsky can benefit from extended time to process stimulation, prompting and a reduction of irrelevant and distracting stimuli. He will be at a disadvantage when he is required to make quick decisions on complex matters."
According to Komisarjevsky's lawyers, these poor decision-making skills were at the root of their clients' inability to stop events from spiraling out of control on July 23, 2007.
Copyright 2011 ABC News Radio