14 News has learned that 25-year-old NealHigdon called his girlfriend and told her about his problems with the supervisor and said he planned to kill his boss at Atlantis Plastics.
But Teresa Ventura never thought he'd actually go through with it.
Ventura lived with Higdon in a Henderson apartment.
She says Higdon made threats in the past about work. And was quick to get angry. But Ventura never believed he'd kill anyone.
"He told her that he had problems with his supervisor. And he told her that he was going to kill him," Ventura told 14 News.
Police are now looking into whether Higdon's girlfriend should face charges failing to notify police about the phone call to her.
"He just walked in and meant business and started shooting at everybody." Detective John Nevels with the Henderson Police Department.
Police say when Higdon arrived for work at Atlantis Plastics at his usual time Tuesday night co-workers knew something was up.
What they didn't know was that night would turn out to be of the one darkest in Henderson County's history.
"The lady that worked next to him at the machine said that he came in at 6 am, when he started his shift, that he was very upset and very mad about everything," said Det. Nevels.
Police say earlier that evening Higdon got into a fight with a co-worker, Joshua Hinojosa, at a convenient store and later that evening had words with his boss.
"The supervisor called the suspect and I guess he was not at his workstation on his cellphone. He [the supervisor] actually had some words with him [Higdon] about slapping the Joshua suspect and he wasn't going to tolerate it and that he was going to have to go home."
Police say when Kevin Taylor, Higdon's supervisor, was escorting him out of the factory Higdon pulled out a 45-caliber handgun and shot Taylor.
Police say Higdon then headed for the breakroom and opened fire there, shooting four of the eight employees in the room.
He then allegedly headed for the factory floor to gun down Joshua Hinojosa, the co-worker Higdon argued with earlier in the night.
In the end Higdon turned the gun on himself.
"He has very little criminal history. He had a possession of marijuana charge, a DUI, and a seat belt ticket," said Det. Nevels.
14 News asked police if this shooting could be racially motivated because several of the victims are hispanic.
Detectives say they don't believe that's the case.