Local and federal law enforcement agents were told more than a year ago that the tech worker who detonated a bomb in downtown Nashville, Tenn., on Friday morning was making explosives in his recreational vehicle, but they said they were unable to investigate further after he did not respond to knocks on his door, according to police documents.

Nashville police visited Anthony Warner's home on Aug. 21, 2019, after a woman who identified herself as his girlfriend at the time, Pamela Perry, told officers that he "was building bombs in the RV trailer at his residence," according to an incident report and synopsis from the Metropolitan Nashville Police Department. The visit was first reported by The Tennessean.

An attorney for Perry, Raymond Throckmorton, also told police at the time that Warner "frequently talks about the military and bombmaking" and was "capable of making a bomb," the report says. The responding officers notified their superiors and the FBI, according to the synopsis, but a background check on Warner did not show suspicious information.

An FBI spokesman said the agency had found "no records at all" after it received a request from the Metropolitan Nashville Police Department on Aug. 22, 2019, to investigate Warner. The FBI also processed a Department of Defense inquiry, "which was also negative," the spokesman said.

Tennessee Bureau of Investigation (TBI) Director David Rausch told reporters this week that Warner "was not on our radar" before the Christmas morning bombing.

A TBI spokesman, Josh DeVine, reiterated Wednesday that the agency "had no information about Warner prior to the event on Christmas." He said that while the TBI often helps local police vet tips they receive, police are not obligated to share that information with state investigators, even when they notify federal authorities.

The blast shattered the Christmas morning calm in the city's entertainment quarter, damaging 41 businesses, sending three people to the hospital with minor injuries and knocking out communication networks throughout the region. Warner was killed in the explosion.

Investigators are working to identify what motivated the 63-year-old recluse to pack his RV with explosives and broadcast a warning telling residents to leave before detonating the explosives outside an AT&T transmission hub. They are investigating whether he had a fascination with 5G conspiracy theories.

The incident report sheds little new light on Warner's mind-set but indicates that he may have been planning the explosion for 16 months or more.

According to the law enforcement documents, police visited Perry's home on the morning of Aug. 21, 2019 after Throckmorton told officers that she made suicidal threats to him on the telephone.

When officers arrived, they found Perry with two unloaded pistols sitting next to her. She told them that the weapons belonged to "Tony Warner" and that she did not want them in the house any longer, according to police.

In the same conversation, Perry told them that Warner was making bombs in his RV, the report states. Throckmorton appeared to back her up, telling officers that Warner "knows what he is doing and is capable of making a bomb," according to the report. After the interview, an ambulance picked up Perry for voluntary psychological evaluation, the report states.

The same day, police went to Warner's home in Nashville's Antioch neighborhood, about 1 [1/2] miles from Perry's house. They said that they noticed the RV parked in the backyard but that they could not see inside because it was blocked by a fence. Officers also reported seeing several security cameras on the property and wires attached to an alarm sign on the front door. The officers reported that they knocked on Warner's door multiple times, but that he did not respond.

"They saw no evidence of a crime and had no authority to enter his home or fenced property," police said in the synopsis.

Officers told supervisors about the incident and sent a report to the hazardous devices unit for follow-up, according to police.

On Aug. 22, police sent a message to the FBI, which soon reported back that agents had found "no records on Warner at all," police said. Subsequent reports from the Department of Defense and the Bureau of Alcohol, Tobacco, Firearms and Explosives turned up nothing suspicious, according to police.

At about the same time, the hazardous devices unit contacted Throckmorton, according to the synopsis.

"The recollection of that call is that Warner did not care for the police," police said in the synopsis. "At no time was there any evidence of a crime detected and no additional action was taken."

Warner had no criminal record aside from an arrest for marijuana possession in 1978.

Reached at his home in suburban Nashville on Wednesday morning, Throckmorton came to the door but declined to comment on the incident.

In an interview with The Tennessean on Tuesday night, Throckmorton said he had urged police to investigate Perry's claim, saying she feared for her safety.

"Somebody, somewhere dropped the ball," Throckmorton told the newspaper.

He added that he had represented Warner in a civil case years earlier but that he was no longer a client in August 2019. "He wasn't an active client. I'm not a defense attorney," he told The Tennessean.

In a brief interview at her home in Smyrna, Tenn., Perry said that she was not Warner's girlfriend but that they had known each other for more than 40 years. She said Warner had threatened her in the past but declined to offer details about what happened.

Over the weekend, law enforcement agents searched Warner's home, which sits about 12 miles southeast of the blast site in a middle-class suburb lined with brick, single-family houses and duplexes. Investigators removed a computer motherboard, among other effects, Warner's next door neighbor told The Washington Post.

The bombing shocked neighbors, who described Warner as an intensely private person who seemed obsessed with home security and rigged his property with cameras and "no trespassing" signs. Some residents said they remembered seeing his RV parked in the backyard months before the explosion.

Investigators said this week they were still in the early stages of determining a motive and cautioned that Warner may not have had a rational reason for his actions. "It could be weeks before we have a comprehensive picture," FBI Special Agent Jason Pack said Monday.

Agents from the FBI and the ATF were combing through the mounds of rubble and mangled metal at the blast site, starting at the outer perimeter and working their way inward.

Law enforcement officials said Tuesday afternoon that federal evidence teams had canvassed nearly half the original crime scene and returned it to the city for cleanup and safety assessments. They're aiming to wrap up their work by Friday, they said.

Other federal agents, including members of the FBI's behavioral analysis unit, are interviewing Warner's associates while lab technicians in Quantico, Va., try to determine what explosives were used in the bomb.

The Washington Post's Devlin Barrett and Louie Estrada contributed to this report.