A former assistant U.S. attorney says that Tyler Robinson’s reason for allegedly killing TPUSA founder Charlie Kirk may be more crucial during the sentencing phase because prosecutors will try to “dirty up” the defendant in hopes that juries will give him the death penalty.

Officials say Robinson killed Kirk at a TPUSA event on September 10 at Utah Valley University in Orem, Utah. He is being charged with aggravated murder, two counts of obstructing justice, criminal discharge of a handgun inflicting serious bodily injury, two charges of witness tampering, and committing a violent crime in front of a child.

Authorities say Robinson is claimed to have killed Kirk because he “had enough of his hatred” and “some hate can’t be negotiated out.”

Robinson is due in court on October 30.

Court papers show that Robinson sent his roommate, Lance Twiggs, a text message requesting him to “look under my keyboard.”

“I had the opportunity to take out Charlie Kirk, and I’m going to take it,” read a note photographed by Robinson’s roommate, according to authorities.

“You weren’t the one who did it right????” the roommate allegedly wrote to Robinson.

“I am, I’m sorry,” Robinson said, according to the court documents.

Neama Rahmani, a former Assistant U.S. Attorney, told Fox News that prosecutors will use this evidence more during the punishment phase to try to get the jury to give Robinson the death penalty.

“The Utah County prosecutor is going to try to put Robinson to death, and the motive for the killing is going to be something that is key evidence in the case. It’s going to dirty up Robinson,” Rahmani said.

Rahmani added that Robinson will only get the death penalty if all 12 jurors agree that he should be killed for his claimed offenses. This makes it even more critical for prosecutors to explain clearly why they think he should be murdered.

“To the extent that the prosecution has to get 12 out of 12 jurors to return that death sentence. The motive for the crime will be an important reason why the prosecution may get there,” Rahmani said.

“So when jurors are weighing the death penalty, the reason why someone killed another human being, if it was for political reasons, that’s certainly an aggravated factor,” Rahmani added.

“Even one or two jurors could save Tyler Robinson’s life. And just from a pure numbers perspective, there are some people that have a difficult time looking another human being in the eye and giving them lethal injection or the firing squad,” Rahmani continued.

“The other possibility, of course, is they try to defend the case in the guilt phase. It’s going to be very hard to defend, but they’ll have to argue some sort of radicalization. It’s going to dirty up Robinson. The jurors are not going to like him because not only is there no legal justification for what he did, but there’s really no moral one whatsoever,” Rahmani said.

While prosecutors are still piecing together a motive, Utah Gov. Spencer Cox said Kirk’s death was a “political assassination.”

He said that one of the bullets allegedly used by Robinson had an engraving that read, “Hey fascist, catch.”

“I think that speaks for itself,” Cox said during a news conference.

Kathryn Nester, Robinson’s lawyer, hasn’t yet responded to prosecutors’ claims about why her client killed Kirk.

However, she did say in court that the defense is reserving the right to ask for a preliminary hearing, where prosecutors would have to show evidence and let Robinson’s lawyer cross-examine witnesses before the case moves forward.