Aurora Police Detective Michael Leiker (LY'-kur) testified during a pretrial hearing in October that he found evidence of the internet search. He didn't say if he knew who did the search or when it was done. Neither prosecutors nor the defense asked him to elaborate.
Holmes pleaded not guilty by reason of insanity to charges of killing 12 people and injuring 70 during the July 2012 attack on a suburban Denver movie theater. Prosecutors are seeking the death penalty.
His trial is scheduled to start in October.
Evidence about Holmes' sanity will be crucial, and prosecutors might be able to use Leiker's testimony about the "rational insanity" search to undermine the defense contention that Holmes was legally insane — could not tell right from wrong.
However, they have not indicated whether they planned to use Leiker's finding in their case.
Also Friday, Arapahoe County District Judge Carlos A. Samour Jr. denied another defense attempt to have Colorado's death penalty declared unconstitutional, and he rejected a series a defense motions about what kinds of arguments prosecutors should be able to make in favor of execution if Holmes is convicted.
Defense attorneys wanted to keep prosecutors from presenting evidence during the penalty phase of the trial that Holmes had shown "extreme indifference," acted in a cruel or depraved manner or showed other traits that could support imposing the death penalty.
Samour was critical of the defense motions, saying they were confusing, incomplete or meritless.
"If the defendant's bald assertions were sufficient to successfully challenge the constitutionality of a statute, no statute could ever withstand a constitutional attack," Samour wrote.
A separate filing by prosecutors that was made public Friday suggested that if investigators are pursuing more evidence, it might involve business records.
The district attorney's office has requested new guidelines covering any future search warrants and document requests in the 21-month-old case, and prosecutors and the defense have been exchanging written arguments about it.
The prosecution filing released Friday said investigators might be interested in a court order to obtain records from an unspecified business. Their previous filing didn't mention what type records might be requested.
Associated Press writer Donna Bryson contributed to this report.
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