Vester L. Flanagan II shot and killed two former co-workers because of workplace grievances and anger from the massacre at a black church in Charleston, S.C., he wrote in a suicide note he sent to ABC News shortly after the killings Wednesday morning.

Flanagan killed Alison Parker, 24, and Adam Ward, 27, while the WDBJ7 reporter and cameraman filmed a live television segment outside Roanoke. Soon after, Flanagan, 41, fatally shot himself in his car while Virginia state police pursued him in Fauquier County.

ABC News said that it called police after receiving the rambling document and a call from someone claiming to be Flanagan after the shooting. Franklin County Sheriff Bill Overton said investigators were looking into the document. “It certainly goes to show where the gentleman’s mind was the night before,” Overton said. “There was some thought given.”

In the document, obtained independently by The Washington Post, the writer refers to several previous shootings.

He seems to admire some shooters. But Flanagan, who writes extensively about his experiences as a black man in the memorandum, was enraged by the Charleston massacre.

Authorities have identified Vester Lee Flanagan as the suspect in the shootings deaths of journalists Alison Parker and Adam Ward during a live TV broadcast near Roanoke, Va. (Jorge Ribas/The Washington Post)

“What sent me over the top was the church shooting,” he wrote. “As for Dylann Roof?. . . You want a race war . . .? BRING IT THEN.”

Flanagan titled his document “Open Letter to a Black Father from a Black Son.”

He said that at one point, his father asked him if he was taking steroids. He said he was not, but “I was absolutely taking energy supplements that caused me to be extremely aggravated.”

Flanagan’s lengthy letter focuses most furiously on his experience at the Roanoke news station.

He complained that he was micromanaged, with a boss telling him what camera angles to use for a story, and that he was not paid for working overtime.

He said that he was mistreated by co-workers at WDBJ because he was black. A photographer asked if he wanted a watermelon Slurpee when they stopped at a 7-Eleven, and another co-worker asked if he had seen cotton growing when they drove past a cotton field, Flanagan said. He interpreted both comments as racial slights. Flanagan, who was gay, also said people insulted him over his sexual orientation.

“WDBJ7 made me snap . . . they sure did. They are responsible for all of this!!!” he wrote.

He referred to the two Columbine High School shooters, and he said he learned from the man who murdered 32 people at Virginia Tech when they practiced at the same shooting range in Roanoke.

“I was influenced by Seung-Hui Cho. That’s my boy right there. He got NEARLY double the amount that Eric Harris and Dylan Klebold got,” he said, referring to the Columbine shooters.