St. Landry Sheriff Bobby Guidroz confirmed that Matthews is the son of a deputy.
Guidroz, the sheriff, spoke of the difficulty of informing deputy Roy Matthews about his son.
"As we all know, Holden's father is an employee of mine, a fine man", Guidroz said.
Matthews, who has no history of violence or previous arrests, posted on social media about his interest in "black metal", a sub-genre of heavy metal rock music that in countries outside the United States has been connected with arson directed at Christian churches. "Across the diaspora, black spiritual and religious spaces - whether a clearing in the woods or a stone and mortar church - have nurtured rebellion, and that's why they continue to be under siege", J.T. Roane, an assistant professor of Women's, Gender, and Sexuality Studies at the University of Cincinnati who studies religion and black communities, said in 2015. "I don't know what was in his heart", Louisiana Gov. John Bel Edwards said at a news conference Thursday morning.
Firefighters and fire investigators at a fire at Mt Pleasant Baptist Church, in Opelousas, Louisiana earlier in April.
The investigation was joined by the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives, and many people from state agencies in Louisiana.
The fires happened within 10 days at similar sites - rural, African American churches fronting small cemeteries.
"Right now we are just making sure we gather all the facts", said FBI agent Eric Rommal, adding that federal investigators are also looking at whether the arson attacks were "bias-motivated".
Officials said they have no reason to believe the fires are related to another incident of suspected arson on 31 March at a predominantly white church a few hours away from the community.
The affidavit filed with Matthews' arrest warrant says a gas can recovered at one of the burned churches was sold at Walmart locations and the company's investigators found that the same type of gas can, along with a lighter, were bought March 25 in Opelousas.
"We've suffered but I think it has a cause, a higher cause", Rev. Gerald Toussaint of Mount Pleasant Missionary Baptist Church said. Pleasant Baptist Church in Opelousas respectively caught fire, according to a statement from the State Fire Marshal's Office.
State Fire Marshal Butch Browning said at a news conference Thursday that he was "confident" that "we have the person responsible for these tragic crimes".
"What is happening in Tennessee and Louisiana is domestic terrorism and we must not turn a blind eye to any incident where people are targeted because of the color of their skin and their faith", Johnson said. "He was shocked and hurt as any father would be". He said there is an "elitist" element of the black metal music scene that is fascinated with those church burnings. "As a effect, these houses of faith have historically been the targets of violence".
According to the latest data from the National Fire Protection Association, fires within religious and funeral properties have been on the decline for decades.