NASHVILLE, Tenn. (AP) — The FBI investigation into whether the Nashville bombing was a terrorist act has sparked criticism about a possible racial double standard and drawn questions from downtown business owners whose insurance coverage could be affected by the bureau’s assessment.

More than a week after an explosion that struck at the heart of a major American city, the FBI has resisted labeling it an act of terrorism, an indication that evidence gathered so far does not conclusively establish that the bomber was motivated by political ideology — a key factor in any formal declaration of terrorism. The bureau is still examining evidence and has not announced any conclusions, but investigators are known to be reviewing whether Anthony Warner believed in conspiracy theories involving aliens and 5G cellphone technology.

Warner died in the Christmas Day explosion of a recreational vehicle that also wounded three other people.

“When we assess an event for domestic terrorism nexus, it has to be tied to an ideology. It’s the use of force or violence in the furtherance of a political or social ideology or event. We haven’t tied that yet," Doug Korneski, the FBI agent in charge of the agency’s Memphis office, told reporters last week at a news conference.

The FBI investigates two types of terrorism that are defined not by the ethnicity or background of the suspect but by the person’s motivation or ideology. International terrorism involves acts by people who are inspired by, or acting at the direction of, foreign terrorist organizations. Domestic terrorism generally involves politically motivated violence intended to further a particular cause or agenda.

The explosion in Music City's historic downtown damaged more than 40 businesses. Since then, a handful of state and city leaders have raised concerns about the terrorism designation, arguing that authorities would have acted differently if the 63-year-old Warner had not been a white man.

“To those bending over backward to not call this an act of terror, if Warner had been a Muslim/immigrant/black, will you say the same thing or will you be one of the millions condemning not just him but his entire community?” Nashville City Council member Zulfat Suara tweeted just days after the bombing.

The classification of the attack could help determine insurance payouts for businesses that were damaged. At issue are the varying definitions of terrorism sprinkled throughout federal law.

Small business owners tend to opt out of terrorism coverage when selecting insurance policies, presuming that a terrorist act would be unlikely to affect their company, said Jason Schupp, founder and managing member of Centers for Better Insurance, an insurance industry think tank near Washington, D.C.

Pete Gibson is owner of Pride and Glory Tattoo Parlor, which is directly across from the bomb site. He said terrorism coverage was the farthest detail from his mind when he was selecting an insurance policy seven years ago. He is still unsure what will be covered, but he has a meeting with attorneys this week to go over his policy.

“I hadn’t even heard of terrorism coverage back then,” Gibson said. “So now it’s just a big mess. I’m hoping to know more soon.”

Gibson said he and other small business owners were approached earlier this year during Black Lives Matter protests about considering terrorism coverage, but they all brushed it aside.

He has been able to visit the bomb site to assess some of the damage, but his tattoo shop is still too unstable to walk through. He described “massive pieces of timber all around and lights flickering.”

According to the Treasury Department, 30% to 40% of Tennessee businesses have excluded terrorism coverage from their policies.

A 2002 federal law — enacted by Congress shortly after the 9/11 attacks — allows the Treasury secretary to certify an event as an terrorist act regardless of how law enforcement officials regard it. To date, the Treasury has never done so, including after the 2013 Boston marathon bombing and the 2017 Las Vegas Strip mass shooting, Schupp said.

Furthermore, domestic terrorism can be challenging to define, especially when it comes to prosecution. Though there is a definition in the U.S. criminal code, there is no federal domestic terrorism statute, meaning that Justice Department prosecutors must turn to other crimes such as explosives charges to prosecute acts that might otherwise be thought of as terrorism.

The Nashville bombing occurred well before downtown streets were bustling with Christmas activity. Police were responding to a report of shots fired when they encountered the RV blaring a recorded warning that a bomb would detonate in 15 minutes. The audio then switched to a recording of Petula Clark’s 1964 hit “Downtown” shortly before the blast.

Investigators have not uncovered a motive, but they have learned that Warner may have believed in conspiracy theories, including the idea that shape-shifting reptiles assume human form to take over society. He also discussed taking trips to hunt aliens, officials said.

The FBI has confirmed that Warner sent materials about his views to people he knew, but investigators have not released details about what the packages contained.

___

Tucker reported from Washington.