A white man charged with killing a black man in a March fire at the veterans halfway house where they both lived reportedly admitted his racial bias in a jailhouse letter to a white supremacist group that was intercepted by deputies.

John Daniel Carothers, 53, was already jailed in Rutherford County on a charge of first-degree murder in the death of 40-year-old Robert Miller, who died of burns to his head and upper torso about a week after the March 17 fire. Carothers is also charged with aggravated arson and seven counts of reckless endangerment, The Murfreesboro Post reported.

The motive behind the arson remained elusive, however, until an Aug. 8 court hearing, at which Murfreesboro police Detective Jacob Fountain, a lead investigator on the case, read a letter Carothers wrote to the white supremacist group, the Post reported.

"To my brothers and sisters in Jesus Christ our savior and Lord, my name is John D. Carothers and I believe the Bible is about white people and for white people," the letter read, in part, according to the Post. "I am in Rutherford County Jail for burning a black man. I set him on fire with lighter fluid poured on his head."

Carothers’ letter also asked the group to send him a study Bible.

The Huffington Post reported that the letter was addressed to the Arkansas-based Kingdom Identity Ministries, the largest publisher in the U.S. of Christian Identity materials.

A website identifying itself as belonging to Kingdom Identity Ministries calls the movement a "politically incorrect Christian Identity outreach ministry to God's chosen race (true Israel, the White, European peoples)." A logo on the homepage of a cross and crown states, "Conquer we must, for our cause is just."

Sixteenth Judicial District Attorney Jennings Jones told NewsChannel 5 in Nashville that the letter was discovered by sheriff's deputies in the jail's outgoing mail.

"It is helpful evidence," Jones told the news station. "The motive does matter."

Tennessee does not have a hate crime law, but Jones and Assistant District Attorney J. Paul Newman, the prosecutor on the case, said the racial motivation of the alleged crime could become a factor at sentencing. The U.S. Department of Justice, which can prosecute a crime as a hate crime, could also intervene, NewsChannel 5 reported.

Lisa Hathaway, a cook for the halfway house where Carothers and Miller lived, said during the Aug. 8 court hearing that it was just after breakfast on March 17 when one of the residents shouted that the house was on fire, according to the Post. Carl Peas, the assistant chief for Murfreesboro Fire & Rescue, testified that the fire started on Miller's bed in a front bedroom, which had several windows broken out.

Testimony in court indicated that Miller was on fire when he ran to a back bathroom and jumped in a shower to extinguish the flames, the Post reported. Afterward, he went out front to await medical help.

Peas testified that he found skin and burned clothes in the shower, the newspaper reported. He determined the fire was arson, started by an accelerant.

Police and firefighters began looking for Carothers after questioning the other residents of the halfway house. Murfreesboro police Officer Quinn Rodriquez found him walking near a convenience store and stopped him.

Carothers was carrying a backpack full of clothes -- and an empty Zippo lighter fluid bottle, the Post reported.

"He said, 'I live in a place I burned,'" Rodriquez testified, according to the newspaper.

Carothers has undergone a psychiatric evaluation, in which he was found competent to stand trial, NewsChannel 5 reported. His case has been bound over to be heard by a grand jury.

The murder charge in Miller's death is not the first that Carothers has faced. The Daily News Journal in Murfreesboro reported that Carothers was convicted of second-degree murder in 1999.

He was also charged with second-degree murder in a second case but pleaded guilty to a lesser charge in 2011. Both cases, for which details were not immediately available, were out of McNairy County.

Tennessee Department of Corrections information shows that Carothers was released from prison in June 2016.