Day is accused of sending messages online that incited violence by Gareth Train, 47, Nathaniel Train, 46, and Stacey Train, 45, at their Wieambilla property.
Gareth Train, 47, Nathaniel Train, 46, and Stacey Train, 45, gunned down Constables Rachel McCrow, 29, and Matthew Arnold, 26, and innocent neighbour Alan Dare, 58, on December 12 last year.
The Trains were shot dead hours later.
Court documents reveal Day allegedly incited violence in videos and comments he made online.
“That’s the only language that evil ever respects, responds to, or understands and that is the language of virtuous violence,” he said in one video.
He also said in another video, “kill these f—— devils”.
Queensland Police Service Assistant Commissioner Cheryl Scanlon said yesterday that Day and the Trains were allegedly in contact for two years before the massacre, watching and commenting on each other’s videos.
The 58-year-old sent “Christian end-of-days ideology” messages to the Trains using the monitor “geronimo’s bomes” from a rural setting outside Heber Overgaard in Arizona.
Scanlon also confirmed Day is connected to a YouTube video posted by the Trains on the night of the confrontation.
“See you at home Don, love you,” Gareth and Stacey Train said in the video after the religious terror attack.
Day was arrested on two indictments one of which relates to comments posted online in December 2022 inciting violence over the Wieambilla attack.
The other allegedly relates to threats made to the Director-General of the World Health Organisation.
He’s pleaded not guilty to two charges of making an interstate threat.
Each carries a maximum five-year prison term.
Today Queensland Police Commissioner Katarina Carroll said she was hopeful more charges would be laid in the future.
Day is slated to face a trial in February next year.