The girlfriend of Anthony Warner, the man who is believed to have detonated the bomb in Nashville on Christmas Day, warned police officers in August 2019 that he "was building bombs in the RV trailer at his residence," according to police reports obtained by The Tennessean.

Why it matters: Although the Tennessee Bureau of Investigation said Warner "was not on our radar" before the explosion, the report from the Metro Nashville Police Department "shows that local and federal authorities were aware of alleged threats he had made," The Tennessean writes.

Details: Raymond Throckmorton, attorney to Warner's girlfriend Pamela Perry, had called authorities on Aug. 21 and said she was having a mental health crisis while sitting on her front porch with firearms, which she later said belonged to Warner.

• Perry told police at the time that Warner "frequently talks about the military and bomb making" and "knows what he is doing and is capable of making a bomb," according to the report.
• Police then went to Warner's home and saw the RV from the outside, but were unable to enter the residence. The report said authorities "saw no evidence of a crime and had no authority to enter his home."
• A day after the officers' visit, they sent the report and Warner's information to the FBI to check its database, but did not find any records on him. An FBI spokesperson told The Tennessean that was "a standard agency-to-agency record check."
• "No additional information about Warner came to the department's or the FBI's attention after August 2019," a Nashville police spokesperson told The Tennessean.

The big picture: An investigation into the Christmas Day explosion is still underway. Federal prosecutors and Nashville police have not yet uncovered a motive.

• Officials said they do not believe anyone else was involved in the bombing, which left three people injured.
• The detonation came from an RV located in downtown Nashville, which played a recording ahead of the explosion telling people to evacuate the area. It then began playing Petula Clark's 1964 song, "Downtown."

Go deeper: Authorities name Anthony Warner as Nashville bomber, say he died in blast