On-air gunman became increasingly volatile before killings

MONETA, Va. -- Vester Flanagan had become increasingly volatile in recent years, picking fights with co-workers and strangers over seemingly mundane incidents or perceived slights well before he fatally shot two former colleagues on live television.

Flanagan offered a variety of motives before he killed himself Wednesday: A rambling 23-page manifesto sent to a national news network described his ambush as revenge for the killings of nine black people inside a church in South Carolina, which prompted federal hate crime charges against a white suspect. On social media, Flanagan claimed his victims, 24-year-old Alison Parker and 27-year-old Adam Ward, had wronged him.

WDBJ-TV's general manager, Jeffrey Marks, flatly denied his employees did anything wrong, noting Flanagan had been fired because of many performance and behavioral problems. Marks said he alone probably was responsible for any workplace conflicts.

The ambush appeared to be planned carefully. Flanagan had contacted ABC News weeks ago with what he claimed was a story tip, had rented what he ultimately used as a getaway car and was carrying possible disguises: extra license plates, a wig, shawl, sunglasses and a hat. After the killing, he texted a friend suggesting he had "done something stupid," investigators wrote in a search warrant.

Flanagan's grudge against the local station dated to 2013, when he sued WDBJ a month after he was fired, claiming racial discrimination.

Court documents show he was fired for what managers called poor performance and an unending stream of conflicts with co-workers. It began within two months of his start at WDBJ, when he was written up for inappropriate behavior.

News director Dan Dennison wrote Flanagan made co-workers feel threatened or uncomfortable. In one case, he lost his temper in a live truck. In another, photographers said he complained about shaky video without having seen it.

When he was fired in February 2013, company memos say he refused to leave, and the station called 911 to have police escort him out of the building. A human-resources representative, Monica Taylor, reported in a memo Flanagan said, "I'm not leaving. I'm going to make a stink, and it's going to be in the headlines."

As Flanagan was being escorted out, he put a wooden cross in Dennison's hand, saying, "You'll need this," according to Dennison.

Ward documented this altercation with his camera, prompting more insults from Flanagan, according to the court records.

Flanagan's lawsuit claims the station's camera operators conspired against him because of his race. It says a watermelon at the station was a racial slur, directed at him.

He asked for a trial by a jury comprised entirely of black women. A judge dismissed the case in July 2014.