He even told one employee, "If I get fired, I'm going to kill every mother ***** r in here" and "I'm going to blow up the police."
But the employee did not report the comments because he believed that Martin was "always making 'off the wall' statements," according to a formal review of the incident.
Martin, 45, was carried through with his threats that very day, fatally shooting five people and injuring six more, five of whom were police officers. He was killed in a shootout at the plant with police.
In addition to shooting at officers and SWAT team members, Martin did not respond to multiple verbal commands to surrender at any time during the incident, State Attorney Joseph McMahon said in the review.
"Based on a review of the investigations, all the officers at the scene of this incident had the reasonable belief that the deadly force they employed was necessary to prevent the death of a great body harm to themselves and other individuals as they attempted to locate and arrest the offender, "McMahon said in his conclusion
What happened on February 1
It seems that Martin brought the gun and ammunition to the plant when he arrived for work that morning, McMahon said in the review, because no video evidence shows he returns to his car before shooting.
The same employee who heard Martin make threats was also aware that Martin carried a gun in his vehicle, the review states. But he had never seen him with a gun inside the building, and he did not know that he brought a gun inside that day.
Martin told several employees that he was concerned that he might be fired for an incident the day before related to safety glasses, according to the review. He also exchanged words about the incident near the time clock with Vicente Juarez, a stock room attendant and fork lift operator.
Shortly after 1 pm, Martin was called to a meeting in an upstairs office. He was spotted walking over his work station, where he retrieved something and put on a hooded sweatshirt. He stopped in the restroom before entering the office.
Human Resources Manager Clayton Park told Martin they would begin the termination process. Martin started cursing, and plant manager Josh Pinkard told him "it's over."
Martin replied, "Yeah, it's over," according to the review.
He opened fire, killing Parks and Pinkard and two other employees in the office, Russell Beyer and Trevor Wehner.
He then went to the loading dock area, where several people saw him shoot Juarez
"It is apparent from the incident that he specifically targeted Mr. Juarez," the review says.