Four of those killed were African-American and evidence is mounting that the incident was a hate crime with colleagues reporting racist incidents involving the killer.

An Assembly-line worker at a Lockheed Martin plant in Mississippi on Tuesday shot dead five of his co-workers and then himself. Four of those killed were African-American.

The evidence that the incident was a hate crime is mounting.

The killer was Doug Williams. Lynette McCall, who is African-American, was one of those murdered by Williams on Tuesday. She had told her husband of several racist incidents involving Williams over the years. Her husband Bobby McCall told The New York Times: “He said he was going to come in one day and kill up a bunch of niggers and then he was going to turn the gun on himself.”

Other examples of Williams’ racism have emerged in the last day.

When he overheard a black man complimenting a white woman a on the factory floor, Williams stepped up to the man, used a racial slur, angrily told him blacks had no business being with blond women, and threatened him. This according to witnesses and company officials.

Last month, a black colleague said the white protective head-covering Williams was wearing looked like a Ku Klux Klansman’s pointy hood. Williams boss told him to take the head-covering off or go home. Williams chose to go home, according to company officials.

The Times reports on Monday, Williams, told his father he was angry that he would have to attend the annual training course on ethics and sensitivity the next morning.

When the training began on Tuesday, Williams was seated at a table with three African-American men. According to witnesses Brenda Dubose, he got up, said “You all can handle this,” and left. He returned moments later with a semi-automatic rifle and opened fire.

Local law enforcement claim it is not clear the shootings were racially motivated. Sheriff Billy Sollie of Lauderdale County claimed it appeared Williams had fired at random. He noted the wounded included four blacks and five whites.

The President of the Lockheed Martin Aeronautics Company, Dain Hancock, initially refused to disclose whether company officials were aware of Williams’ history of racism and potential for violence.

The Lockheed Martin factory he worked in built parts for the C-130J Hercules and F-22 Raptor jets.

• Brenda Dubose, an African American worker at Lockheed Martin who suffered minor injuries in the shotgun attack by Doug Williams.
• Erica and Jonathan Willis, children of Thomas Willis who was one of the Lockheed Martin workers gunned down on Tuesday by Doug Williams.