By Eric Levenson and Rebekah Riess, CNN

(CNN) -- The man who detonated a vehicle bomb in downtown Nashville on Christmas morning sent "materials which espoused his viewpoints" to several acquaintances throughout the country, FBI public affairs officer Darrell DeBusk told CNN.

The materials could provide further information on the motive of the bomber, identified as 63-year-old Anthony Quinn Warner. DeBusk asked those who received the material to contact the FBI.

Warner, from Antioch, Tennessee, died when his RV exploded on 2nd Avenue North, injuring at least eight people and damaging more than 40 buildings, including an AT&T transmission building. In the moments before the explosion, his RV broadcast ominous warnings in a computerized female voice that it would soon explode. The unusual warnings spurred police and bystanders to leave the area and limited the human toll.

Warner's neighbors and a person he worked with had little substantive to say about him. They described him generally as a loner and a computer expert.

The warnings and sparse evidence of Warner's politics have prevented authorities from calling the bombing an act of terrorism, which by definition is an act in furtherance of a political goal.

Police had been told he was building bombs

Though his motive remains unclear, Warner's bomb-making capability had previously been reported to police.

A woman who said she was Warner's girlfriend told police last year he was making bombs in his RV, according to a statement and documents the Metropolitan Nashville Police Department provided to CNN.

On August 21, 2019, police received a call from an attorney representing Pamela Perry, the woman who said she was Warner's girlfriend, the MNPD said last Tuesday. Her attorney, Raymond Throckmorton, said she had made "suicidal threats to him via telephone."

When police arrived at Perry's home, they found two unloaded pistols near Perry, who said they belonged to Warner. She told officers she did not want them in the home any longer and that Warner was "building bombs in the RV trailer at his residence," according to a "matter of record" report from the MNPD.

The police also spoke to Throckmorton, who once represented Warner and was also at Perry's home. He told authorities Warner "frequently talks about the military and bomb-making. (Throckmorton) stated that he believes that the suspect knows what he is doing and is capable of making a bomb," the report said.

CNN has reached out to Throckmorton for comment about his account -- first reported by the Tennessean -- but has not heard back.

An officer observed Warner's home for several days, but found no evidence of bomb-making, according to Metro Nashville Police Chief John Drake. It would have taken a sign of a crime being committed, or that a bomb was being made, to obtain a legal search warrant or subpoena, Drake said.

"I believe officers did everything they could legally. Maybe we could have followed up more -- hindsight is 20/20," Drake said. "The officers did not have probable cause to get a search warrant. There was a call for service on a lady who had two guns, who needed care, and so we, you know, she needed some assistance. There was nothing else there to say OK, yeah -- you have to have probable cause."

An officer asked Throckmorton over the phone whether he could look inside the RV behind the home. The attorney told the officer Warren "did not care for police" and "I'm not going to be able to let y'all do that," according to Drake.

Throckmorton denied those claims in an interview with CNN affiliate WTVF.

"He was not a current client of mine at that point in time," Throckmorton said. "I certainly would have never have told him not to check it out when I'm the one who said, go the hell over there, find out what's going on."