(CNN) - Holden Matthews, 21, has been charged in connection with fires at three historically black churches in Louisiana.
While the motive is still under investigation, authorities said that Matthews' interest in black metal music may have influenced his behavior.
"Information investigators have uncovered, and that Matthews has offered, suggests a possible connection with a genre of music called 'black metal' and its associated history with church burnings in other parts of the world, which have been documented in movies and books," the state fire marshal's office said in a statement.
Here's what you need to know about this musical genre.
What is black metal?
Black metal is a subgenre of heavy metal music that typically takes on anti-Christian, satanic and paganistic themes. Black metal songs typically have a fast tempo and feature shrieking vocals, heavily distorted guitars and unconventional song structures.
Black metal dates back to the early 1980s, in what's called the genre's first wave, when the English band Venom released its second album titled "Black Metal." Stylistically, the music was similar to earlier heavy metal subgenres, but Venom's lyrics had anti-Christian and satanic themes. Bands like Bathory and Hellhammer were also early influences, incorporating shrieking and lo-fi production.
First wave musicians also adopted morbid stage personas, pseudonyms and corpse paint that carried on to future iterations of black metal.
In the early 1990s, Norwegian bands like Mayhem, Darkthrone and Immortal formed black metal's second wave, distinctly influencing the nihilistic and misanthropic tone the genre took on.
After the second wave, black metal branched out into even more sub-genres like atmospheric black metal and melodic black metal, with scenes iacross the globe. Some black metal sub-genres represent hateful ideologies, like National Socialist Black Metal, which promotes Nazism and similar views.
The genre has been linked to church burnings
Early black metal bands used evil slogans and satanic imagery for shock value, but the Norwegian black metal scene in the '90s turned those themes into reality.
The most prominent example is Norwegian black metal artist Varg Vikernes, former bassist for the band Mayhem, who was a key player in both black metal and the neo-Nazi movement.
In 1992, Vikernes started a campaign of church burning in Norway, allegedly beginning with the 12th century Fantove Stave Church outside Bergen, according to the Los Angeles Times.
Vikernes boasted about burning churches with other members of the scene, saying he wanted to take "revenge" on Christians and bring Norway back to its pagan roots, Rolling Stone reported.
Vikernes spent 15 years in prison for arson and for the 1993 murder of his bandmate Euronymous.
But while there are subcategories of black metal that express racist or neo-Nazi views, such extremist views aren't representative of the whole genre or the black metal community.
Louisiana suspect's Facebook activity
Matthews was active in a few Facebook groups that focused on either black metal or heathenistic, Asatru and Nordic religious beliefs.
Matthews said in a Facebook post that he held Asatru religious beliefs, which center around old Norse gods.
In two Facebook posts on October 24, Matthews appears to admit he illegally carries a handgun, in addition a knife and dagger.
"I carry this," he wrote, captioning a photo of a handgun. "Maybe not legally but I only truly follow the law of Odin..... which says as you said,arm yourself."
On the same day authorities say Matthews set fire to Greater Union Baptist Church in Opelousas, Louisiana, Matthews made a chilling post in a black metal artists Facebook group.
Another group member asked people to choose a "class": wizard, fighter, sniper, assassin, guardian and warrior.
"I'll take the Arson/assassin/bard," Matthews responded.
Suspect targeted black churches
It's unclear what type of black metal Matthews listened to and whether or not it shaped his world view or influenced his attacks on the churches.
Of course, the question of race in the Louisiana fires can't be ignored -- all three of the churches burned had predominantly black congregations. As such, the events in Louisiana also conjure up painful memories from the Jim Crow era, when church burnings inspired by hatred were common, particularly in the South.
"For decades, African-American churches have served as the epicenter of survival and a symbol of hope for many in the African-American community," NAACP President and CEO Derrick Johnson said. "As a consequence, these houses of faith have historically been the targets of violence."
Authorities have not said whether they also plan to charge Matthews with a hate crime.