More than a year before Anthony Warner detonated a Christmas Day bomb in downtown Nashville, officers visited had his home after his girlfriend told police he was building bombs in a recreational vehicle at his residence, according to documents.
But they did not make contact with him, or see inside his RV.
Those revelations, contained in a newly disclosed 2019 incident report, put Nashville's police chief on the defensive on Wednesday as he said his officers did nothing wrong and that they had handled the situation properly.
He added that other than a 1970s marijuana-related arrest, Warner was "squeaky clean".
"I believe the officers did everything they could legally. Maybe they could have followed up more, hindsight is 20/20," Metro Nashville Police Chief John Drake said at a news conference.
Officers were called to Pamela Perry's Nashville home on August 21, 2019, following a report from her attorney that she was making suicidal threats while sitting on her front porch with firearms, the police department said in a statement.
According to the incident report, when officers arrived, police said she had two unloaded pistols beside her on the porch.
She told them the guns belonged to "Tony Warner" and she did not want them in the house any longer. Perry, then 62, was taken for a psychological evaluation after speaking to mental health professionals.
"During that visit, before leaving for the evaluation, Perry told police that her boyfriend was making bombs in an RV," the report stated.
The report says police went to Warner's home, about 2.4 kilometres away, but he didn't answer the door when they knocked repeatedly.
They saw the RV but it was in a fenced-off backyard and officers couldn't see inside the vehicle. They also spotted several security cameras and wires attached to an alarm sign on a front door.
"They saw no evidence of a crime and had no authority to enter his home or fenced property," the police statement said, adding supervisors and detectives were then notified.
"If we could have had more to go off of, it would have been good," Drake said.
Law enforcement officials did not publicly release the report, which was obtained only after news outlets submitted public records requests.
Later, the Tennessee Bureau of Investigation announced that Warner's only arrest was for a 1978 marijuana-related charge.
Wednesday's developments came as federal agents were continuing to examine Warner's digital footprint and writings, a law enforcement official said.
The bombing occurred Christmas morning well before downtown streets were bustling with activity.
Police were responding to a report of shots fired on Friday when they encountered the RV blaring a recorded warning that a bomb would detonate in 15 minutes.
Then, inexplicably, the audio switched to a recording of Petula Clark's 1964 hit Downtown shortly before the blast. Dozens of buildings were damaged and several people were injured.
Investigators have not uncovered a motive.