Updated

The suspect who authorities say was responsible for the Christmas Day bombing in Nashville reportedly told his neighbor in the days before the explosion that "Nashville and the world is never going to forget me."

Rick Laude said he saw Anthony Quinn Warner standing at his mailbox while driving on Dec. 21. Laude pulled over his car to speak with Warner and after asking how Warner's elderly mother was doing, Laude said he casually asked Warner, "Is Santa going to bring you anything good for Christmas?"  Laude said Warner smiled and then said, "Oh, yeah, Nashville and the world is never going to forget me."

This undated image posted on social media by the FBI shows Anthony Quinn Warner. ((Courtesy of FBI via AP))

Laude, 57, a commercial truck driver, said he didn't think much of the remark and thought Warner only meant that "something good" was going to happen for him. He said he was "speechless" later when he read that authorities had identified Warner as the suspected bomber.

"Nothing about this guy raised any red flags," Laude said. "He was just quiet."

Authorities are working to determine a motive behind the explosion that damaged dozens of downtown buildings and injured three people. 

NASHVILLE BOMBING SUSPECT ANTHONY QUINN WARNER DIED IN EXPLOSION, POLICE CONFIRM

"We hope to get an answer. Sometimes, it's just not possible," David Rausch, the director of the Tennessee Bureau of Investigation said in a Monday interview on NBC's "Today" show. "The best way to find a motive is to talk to the individual. We will not be able to do that in this case."

Authorities say Warner was not on their radar before the explosion. A TBI records report released Monday showed that Warner's only arrest was for a 1978 marijuana-related charge.

"It does appear that the intent was more destruction than death but again that's all still speculation at this point as we continue in our investigation with all our partners," Rausch said.  

Investigators continue to look through the site of an explosion Monday, Dec. 28, 2020, in Nashville, Tenn.  (AP)

Officials have not provided insight into why Warner selected the particular location for the bombing, which damaged an AT&T building and disrupted cellphone service and police and hospital communications in several Southern states as the company worked to restore service.

A source close to the investigation told the Daily Mail that Warner's father, who died in 2011 of dementia, worked for BellSouth, which was acquired by AT&T in 2006.  The source said Warner was believed to be "heavily" into 5G conspiracy theories -- particularly that the networks were supposedly killing people. 

"The unofficial motive thus far is the suspect believed 5G was the root of all deaths in the region and he'd be hailed a hero," the source said. "We are waiting on the digital footprint that should finally provide us with some answers." 

AT&T runs a 5G wireless network across the country, which the telecommunications giant says reaches more than 225 million Americans. 

Forensic analysts were reviewing evidence collected from the blast site to try to identify the components of the explosives as well as information from the U.S. Bomb Data Center for intelligence and investigative leads, according to a law enforcement official who said investigators were examining Warner's digital footprint and financial history, as well as a recent deed transfer of a suburban Nashville home they searched.

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Federal agents, meanwhile, were examining a number of potential leads and pursuing several theories, including the possibility that the AT&T building was targeted.

The bombing took place on a holiday morning well before downtown streets were bustling with activity and was accompanied by a recorded announcement warning anyone nearby that a bomb would soon detonate. The audio switched to a recording of Petula Clark's 1964 hit "Downtown" shortly before the blast.

Warner, who public records show had experience with electronics and alarms and who had also worked as a computer consultant for a Nashville realtor, had been regarded as a person of interest in the bombing since at least Saturday, when federal and local investigators converged on the home linked to him.

Officials said their identification of Warner relied on several key pieces of evidence, including DNA found at the explosion site. Investigators had previously revealed that human remains had been found in the vicinity.

In addition, investigators from the Tennessee Highway Patrol recovered parts from the RV among the wreckage from the blast and were able to link the vehicle identification number to an RV that was registered to Warner, officials said.

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"We're still following leads, but right now there is no indication that any other persons were involved," FBI agent Dough Korneski told reporters. "We've reviewed hours of security video surrounding the recreation vehicle. We saw no other people involved."

The Associated Press contributed to this report.