CENTENNIAL, Colo. (AP) - The jury in the Colorado theater shooting trial heard excerpts Tuesday from a notebook in which defendant James Holmes detailed plans for the shooting and described his "obsession to kill" since childhood.
Prosecutors say the notebook sent by Holmes to a psychiatrist just before the attack is evidence he was sane at the time.
The contention stands at the heart of the prosecution case, which is also expected to include testimony from two court-appointed doctors that Holmes was sane when he opened fire on a packed midnight showing of a Batman movie.
The notebook offered the first glimpse into Holmes' mental state during the shooting. A gag order previously kept those details secret.
Holmes has pleaded not guilty by reason of insanity in the attack that killed 12 people and injured 70 in July of 2012.
While testifying. Aurora police Detective Sgt. Matthew Fyles read passages from the notebook, including one in which Holmes detailed the "obsession to kill" since he was a child and how to carry it out.
Holmes also wrote that problems that led him to withdraw from a graduate neuroscience program at the University of Colorado shouldn't be viewed as a reason for his violence.
The "causation is my state of mind for the last 15 years," he wrote.
Holmes dismissed biological warfare and serial murder as ways to act out his obsession and instead chose what he called a "mass murder/spree." He wrote that he considered attacking an airport but didn't want to be mistaken for a terrorist.
"The message is there is no message," Fyles said Holmes wrote.
Holmes also wrote he needed to research firearms along with the law and mental illness, Fyles said.
Fyles said the notebook was mailed to Holmes' psychiatrist, Lynne Fenton, in a white bubble mailer with a total of 16 "Forever" stamps depicting various scientists.
The mailer contained twenty $20 bills, some of which were dispersed throughout the notebook, and the bills were all burned to some extent.
While cross-examining the detective, defense attorney Daniel King said Holmes wrote death is "life's fallback solution to all problems." In another section, Holmes said, "the real me is fighting the biological me."
Prosecutors have focused on portions of the notebook that detail Holmes' planning of the attack. However, King said confusing musings about Holmes' life make up a greater part of the notebook.
Jurors were given copies of the notebook to read themselves.
Inside the mailer, authorities found a sticky note marked with a circle with the numeral one and the infinity sign inside - the same symbol found on a calendar in Holmes' apartment on the date July 20, 2012, the day of the shooting.
The words "who, what, where, when, why and how" were written on the back of the note, the detective testified.
The first month of Holmes' death penalty trial was dominated by dramatic and emotional accounts of survivors, technical testimony from investigators, and the recollections of Holmes' neuroscience professors and classmates, who said he never seemed detached from reality.
District Attorney George Brauchler has promised to show jurors days' worth of interviews with Holmes by psychiatrists William Reid and Jeffrey Metzner. Both doctors determined Holmes suffered mental illness but was sane at the time of the shootings.
Holmes' lawyers disagree, saying his mind was so distorted by schizophrenia that he could no longer tell right from wrong. They plan to call at least two doctors of their own who also interviewed Holmes and found he suffered a serious psychotic illness.
Jurors could also hear from Fenton, who treated Holmes at the University of Colorado and expressed concerns about him to campus police after he sent her threatening text messages.
If jurors find Holmes not guilty by reason of insanity, he would be sent indefinitely to a state psychiatric hospital. Prosecutors are urging them to find Holmes guilty and sentence him to be executed.