Prosecutors in the murder trial of Jeremy Christian want to introduce a recording of him ranting on public transit to prove he planned to stab anyone who challenged his racist diatribes.

A Dec. 6 motion by the Multnomah County District Attorney's Office asks Judge Cheryl Albrecht to admit a cellphone video taken on a TriMet MAX train on May 25, 2017—the night before Christian fatally stabbed Taliesin Namkai-Meche and Ricky Best.

"I'm about to stab some motherfuckers," Christian says in the recording. "Call the police. I dare you. Let's do this shit."

The existence of the cellphone video has been previously reported. But the request by prosecutors is significant because it suggests a key argument in their case: "The stabbing of Ricky Best, Taliesin Namkai-Meche and Micah Fletcher was not a spur-of-the-moment response to the situation," they write, "but rather were consistent with the defendant having previously contemplated the idea of stabbing people on public transportation."

Making that case to a jury is important because, as the Dec. 6 filing shows, the moments immediately before Christian stabbed Best, Namkai-Meche and Fletcher included a shoving match, which defense lawyers could use to argue that Christian acted without premeditation.

The filing describes these moments: Christian shoved Namkai-Meche, then Fletcher shoved Christian, twice, toward the door of the train car.

The account continues: "The defendant produced a folding knife in his right hand [and] audibly taunted Mr. Fletcher saying, 'Go on! Hit me again!' Mr. Fletcher pushed the defendant again. The defendant then opened the blade of his knife, swung his right hand in one motion and stabbed Mr. Fletcher in the neck."

The motion argues that Christian was seeking exactly this confrontation—and his racist rant on May 26, 2017 was intended to provoke a response. Prosecutors want to introduce the recording to show him voicing this plan. "The evidence is further admissible," they write, "to show the defendant contemplated a plan and developed an intent to retaliate by stabbing any individual on public transportation who challenged his views."

Christian's trial is scheduled to begin Jan. 21.