A note found in the car of a man charged with opening fire on a Tennessee church on Sept. 24 referenced the deadly 2015 shooting carried out by a white supremacist at a black church in Charleston, S.C.

Law enforcement officials told the Associated Press that the note was summarized in an investigative report circulating among law enforcement. Two officials read some of the note's contents to the AP but the outlet did not view the document.

The note could provide insight into what Emanuel Kidega Samson, 25, was thinking during the time of the shooting at the Burnette Chapel Church of Christ in Antioch, Tenn., where one woman was killed and seven others were injured.

Samson, who is black and came to the United States from Sudan as a child in 1996, has been charged with murder for the attack. He is a U.S. citizen. The FBI and U.S. attorney's office in Nashville have opened a civil rights investigation into the shooting.

According to law enforcement officials, the note referenced revenge or retaliation for Dylann Roof, a white supremacist convicted of killing nine black worshippers at a Charleston, S.C. church in 2015.

It is unclear what exactly Samson wrote or whether the note provides further details that could speak to his motivation or state of mind; law enforcement officials are not allowed to publicly discuss the ongoing investigation.

Samson had expressed suicidal thoughts in June and had a relationship with a woman that twice involved police intervention this year, according to police records.