The suspect arrested in the fatal shooting Charlie Kirk had an “obsession” with the conservative influencer, based on the alleged shooter’s digital footprint, FBI Co-Deputy Director Dan Bongino said Monday on Fox News.

Tyler Robinson, a 22-year-old Utah native, is accused of fatally shooting Kirk during an event at Utah Valley University on Aug. 10.

Bongino said the suspect appeared to have exhibited “multiple warning signs.”

“I believe co-workers stated he had detached himself when the topic of politics came up and walked away,” Bongino said on Fox News.

Bongino said they are looking into whether anyone knew the shooting could happen and didn’t alert authorities, referring to online chats Robinson allegedly had about Kirk.

“Did they … hear it and think it was a joke? That is what we’re trying to find out now,” he told Fox News. “If there is a larger network here, we will get that out to the public as soon as we can.”

FBI Director Kash Patel also announced on “Fox & Friends” that DNA found at the crime scene, specifically the towel wrapped around the firearm used in the shooting, and on a screwdriver, links Robinson to the killing of the conservative influencer.

Robinson was arrested last week for felony discharge of a firearm, aggravated murder and obstruction of justice, according to probable cause documents, and was booked into the Utah County Jail.

Charging documents against Robison are expected to be filed early this week, Utah Gov. Spencer Cox said on Friday.

Robinson was apprehended after his father recognized him in photographs released by authorities, Cox said on Friday. His father told Robinson to turn himself in, with the 22-year-old initially saying no, but later changing his mind, officials said.

The father then called a youth pastor, who is also a U.S. Marshals task force officer. The officer advised the father to have Robinson stay in place. This information was then conveyed to the FBI.

Cox thanked Robinson’s family, who “did the right thing.”

Investigators also interviewed a family member of Robinson who said the suspect had “become more political in recent years,” Cox said.

In a recent incident the family member detailed to investigators, Robinson came to dinner and in a conversation with another family member he mentioned Kirk was coming to Utah Valley University. They talked about why they didn’t like him and his viewpoints.

President Donald Trump, who announced Friday on “Fox & Friends” that the suspected shooter was in custody, said Robinson should get the death penalty.

“In Utah, you have death penalty, and a good governor there, I have gotten to know him,” Trump said of Cox. “The governor is intent on the death penalty in this case and he should be.”

Before the arrest of the alleged shooter, officials said they had obtained “good” video footage of the individual and were able to track the movements of the suspect.

On the day of the shooting at approximately 11:52 a.m., the suspect arrived on the Orem campus and then proceeded to travel through the stairwells up to the roof of the building near where the outdoor event was taking place, before the suspect fired down at Kirk, Utah Department of Public Safety Commissioner Beau Mason said last week.

Kirk was hit by a single shot at approximately 12:20 p.m. and taken to a hospital, where he was pronounced dead, authorities said.

After the shooting, the suspect traveled to the other side of the building, jumped off and fled off-campus into a neighborhood, Mason said.

On Friday, Erika Kirk, the conservative commentator’s wife, said “no one will ever forget my husband’s name.”

“You have no idea the fire that you have ignited within this wife, the cries of this widow will echo around the world like a battle cry,” Erika Kirk said on Friday in her first public message since her husband’s death.

ABC News’ Luke Barr contributed to this report.