Lawyers for the Colorado cinema shooting suspect plan to subpoena a Fox News journalist who was the first to report that James Holmes sent his psychiatrist a notebook full of violent descriptions.
The lawyers made the statement towards the end of a court hearing after nine different law enforcement officials denied being the ones to tell reporter Jana Winter about the notebook.
The defence argues the disclosure was a violation of a gag order in the case and is seeking sanctions against the leaker.
After authorities seized a package from Holmes in the mailroom of the University of Colorado, Denver, four days after the shooting, Winter reported that it contained a notebook with violent descriptions of a possible attack.
Defence lawyers quickly complained that the leak must have come from law enforcement and demanded sanctions, though prosecutors said the report was inaccurate and there was no indication it came from anyone with knowledge of the case.
The defence's plans to subpoena Winter could set up a courtroom clash over reporters' ability to protect their sources from disclosure.
In a statement, Fox said the network had not received a subpoena and would evaluate it if one did arrive.
Holmes sent a package containing the notebook and burnt paper money to his psychiatrist shortly before allegedly opening fire on a midnight screening of the latest Batman movie in July.
Authorities have not described the notebook's contents.
Aurora Police Detective Alton Reed testified that he thumbed through the notebook to see if any burnt currency remained inside but did not stop to look at any of the pages and was not able to make out any writing.
"I just kind of fanned through it with my thumb," Reed said.
Aurora Police Sergeant Matt Fyles testified that his department and university police disagreed over which department had jurisdiction over the notebook.
Aurora police obtained a warrant hours after the notebook was found and took custody, but Sgt Fyles did not describe how the disagreement was settled. The notebook was later turned over to the court.
Holmes is charged with killing 12 people and wounding 70. A preliminary hearing to determine if there is enough evidence for Holmes to stand trial is scheduled for January 7.