New evidence has emerged in the fourth week of Dominic Johnson's trial for the murder of David Grunwald.

A video investigators have known about for almost two years, but were unable to find in the suspect's social media records and the records of other people involved but not charged in the case has been recovered.

Johnson is one of four people accused of beating and killing of 16-year-old Grunwald on the night of Nov. 13, 2016.

A jury convicted co-defendant Erick Almandinger on nine counts, including first-degree murder, earlier this year.

That's when the topic of the video first came up, but Alaska State Trooper Sgt. Tony Wegrzyn said investigators never saw the video for themselves.

On Thursday, troopers arrested 18-year-old Andrea Cullington on a material witness warrant after she failed to respond to a subpoena to testify in Johnson's trial.

State prosecutors met with Cullington that afternoon where she showed them the video that was sent to her after the suspects had been arrested.

The video initially came from a juvenile who said it was time-stamped Nov. 13, 2016 at 5:26 p.m., which would have been just a few hours before Grunwald was killed.

Judge Gregory Heath read a transcript of the video.

"First of all it's an indiscernible line," he said. "Then (it) goes 'As hard as I can, in the head just to try to hurt him, just to try to f---ing hurt him.'"

(Viewer warning: Explicit language)

The juvenile, whom KTVA cannot name because she's underage, testified the video was taken in her shed, but she couldn't remember if she was the one who recorded it. She admitted to being on drugs and alcohol at the time and said she couldn't recall the events clearly.

She believed the other suspects in Grunwald's death — Almandinger, Bradley Renfro and Austin Barrett — were also in the shed at the time.

Palmer District Attorney Roman Kalytiak said the video showed Johnson's state of mind the day Grunwald was killed, as well as the other suspects' reaction.

"The video definitely shows people are getting amped-up when he is talking about doing this," Kalytiak said. "Others are chiming in and repeating his last phrase, 'Just to try to f---ing hurt him.'"

Defense attorney Lyle Stohler objected to the video being admitted as evidence for several reasons, including the content of the video and the late notice of its finding.

Stohler asked for a long continuance of the trial so he could determine how to proceed, then asked for a mistrial.

"They're trying to say this is a confession of my client admitting to the assault. We've been preparing for this trial for quite some time. There's been extensive motion work done in this case," Stohler said.

The discussion about whether the judge would allow the video as evidence dominated the entire afternoon. Heath excused the jury as attorneys on both sides argued their case, at times sniping at each other.

"We didn't argue it was a confession," Kalytiak said.

"They argued...let me speak," Stohler said.

"Not if you lie..." Kalytiak responded.

"It's funny being called a liar by this man," Stohler said, pointing at the district attorney.

"Okay, stop it, gentlemen," the judge intervened.

Wegrzyn, the trooper who testified about the video, was called in to discuss why investigators weren't able to find it sooner. He said the clip did not appear in any of the Facebook or Snapchat records troopers received from their search warrant.

Wegrzyn said Cullington refused to speak with investigators when she was initially interviewed in March 2017.

"To this day, I'm still surprised we have that video," Wegrzyn said.

On Snapchat, Wegrzyn noted, any messages that are sent expire seconds after they're received.

"When we didn't find it on any search warrants, it really wasn't a surprise to me. We figured it had gone into Snapchat abyss and was never to be found," Wegrzyn said.

Cullington was also brought to the witness stand to testify about where she found the video. She explained it was in a Snapchat conversation with the juvenile witness.

Throughout her testimony, she looked over to Johnson several times.

Cullington said she had shown the video to Johnson's mother, Misty Johnson, the day she received the message.

"I assume you were Dominic Johnson's friend. Why would you show that to his mother?" Kalytiak asked.

"I guess I wasn't thinking clearly due to the fact I was under (the influence of) substances," Cullington said after a long pause.

After the witness testimony, Heath ruled the video would be admitted as evidence.

"Clearly it's probative of what was going through the mind of Dominic Johnson the night this occurred," Heath said. "He's talking about injuring someone and doing a violent act in the head to hurt an individual. He doesn't say the name David Grunwald, but that can be open for argument."

Heath said the video would be played for the jury on Wednesday, giving Johnson's defense time to determine how it will proceed with the case.

Correction: An earlier version of this story stated that David Grunwald was killed Nov. 13, 2013. The date was actually Nov. 13, 2016. This has been corrected.

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