Alien lizards after the Nashville bombing? The FBI investigates if the terrorist believed in crazy theories

By Tom Winter, Michael Kosnar and Wilson Wong - NBC News

Federal investigators are exploring whether there may be any conspiracy theories behind the motives of the terrorist who set off a bomb on Christmas Day in front of an AT&T building in Nashville, including the possibility that the man

believed in the lizardmen.

 two senior police officials told our sister network NBC News on Wednesday.

Investigators are expected to wrap up their work at the crime scene this week, but it

could take several more

until they identify what motivated Anthony Quinn Warner, who died in the bombing.

[The girlfriend of the Nashville terrorist tipped off a year ago that he was making bombs.

The police "saw no evidence"]

Authorities have been investigating Warner's digital devices, which an official said hold a

large number of images, videos and writings

,

since Saturday

for clues as to what led the man to detonate a powerful bomb inside his mobile home that it destroyed communication networks and injured several people in downtown Nashville.

Specifically, investigators are looking into the suspect's previous trips to an undisclosed location in Tennessee where he camped out in his motor home and, according to statements the suspect made to others,

was hunting for possible aliens

, authorities said.

They reveal the photo of Anthony Quinn Warner, author of the attack in Nashville

Dec. 28, 202000: 31

Additionally, investigators are aware of statements Warner made about a bogus internet conspiracy that

powerful politicians and Hollywood celebrities, such as Bill and Hillary Clinton, Justin Bieber, and Barack and Michelle Obama, are actually lizards

or other reptiles of extraterrestrial origin, which are responsible for a series of historical tragedies, and which are taking over society, officials said.

Federal investigators have also asked Warner's acquaintances if he believed in

conspiracy theories, also unfounded, about AT&T and 5G mobile service

and if that was a motivation for choosing the building of this telephone company for the attack.

[Man robs Washington DC pizzeria fueled by false conspiracy theory]

A senior police officer said investigators have launched a wide network that encompasses family, friends, neighbors, acquaintances and

businesses where they may have purchased supplies to make bombs.

Some people were difficult to locate due to the Christmas holidays, the official said.

More than a year before the bombing, Warner's girlfriend had warned police that he was building bombs in a motor home parked at his home, according to police reports.

Police investigate almost 500 clues to find the person responsible for the explosion in Nashville

Dec. 26, 202002: 36

On August 21, 2019, an attorney for Warner's girlfriend told officers that Warner

"talks frequently about the military and bomb-making,"

according to an incident report released by the Metro Nashville Police Department.

The attorney's call led officers to visit Warner's home, where they knocked on the door without success, according to the report.

Officers wrote that they saw

"multiple security cameras and cables connected to an alarm at the front door,"

the report says.

["Nashville will never forget me": the strange life of the terrorist and what he did before the explosion "]

Officers said they saw a motorhome parked behind a fence in the backyard, but could not see inside the vehicle.

Authorities identified a motorhome linked to Warner as the source of the explosion.

Police said Wednesday that officers at the time saw no evidence of a crime and had no authority to enter the property or the fenced backyard.

They also determined that

the girlfriend needed a "psychological evaluation"

and was taken to a hospital, according to police.

They release a new video of the Nashville explosion and details of the perpetrator of the attack

Dec. 28, 202000: 29

The day after officers visited Warner's home, police sent an incident report to the FBI, which said they asked the agency and the Department of Defense to run a background search on Warner.

Police said they

searched both of their databases and found no results.

The Metro Nashville Police Department did not say it asked the FBI to open an investigation into Warner, but said its Dangerous Devices Unit followed up on the incident report with the attorney.

According to police, the attorney told the department that

Warner "did not like the police"

and would not allow a visual inspection of the motorhome.

[Human Remains and Recording: Nashville Explosion Raises New Questions]

David Rausch, director of the Tennessee Bureau of Investigations, told reporters this week that

the agency did not have Warner on its radar prior to the bombing

, except for an arrest for marijuana possession in 1978.

A spokesperson for the Tennessee Bureau of Investigation told NBC News on Wednesday that

they were unaware of the incident

involving the Metro Nashville Police Department and Warner's girlfriend.

The perpetrator of the Nashville blast was killed in the bombing, according to federal officials.

Dec. 27, 202000: 54

The spokesperson said in a statement: "To be clear, the comments our director made that 'it's not on our radar' were specific to our agency and not to all police forces."

Unlike other cases, such as Boston Marathon bomber Dzhokhar Tsarnaev or Orlando Pulse Nightclub attacker Omar Mateen, the FBI said he was only asked to run a database search for Warner and

not asked him to open an investigation.

[A 63-year-old man is identified as the author of the explosion in Nashville after analyzing the DNA of the human remains found at the site]

The Metro Nashville Police Department did not immediately respond to a request for comment Wednesday.

Warner, 63, who

was described as a "loner"

by some people who knew him, had recently retired as a technology consultant, NBC News reported Monday.

A member of police walks past damage from an explosion in Nashville, Tennessee, Friday, Dec. 25, 2020.AP Photo / Mark Humphrey

Officers were responding to several reports of shooting in the area on Christmas morning when they heard a recording with a warning about an explosion coming from a motor home in front of the AT&T building.

Authorities said the blast, which they believe was set off by Warner, occurred at 6:30 a.m. last Friday and spread across several blocks of downtown Nashville.

The blast

injured at least three people

and damaged more than 40 nearby businesses.

Warner was the only person who died in the explosion.