John Robert Neumann Jr., a 45-year-old Army veteran, walked into the Orlando business he was fired from months ago shooting and killing five of his former coworkers Monday, authorities said.
As investigators try to determine what led to the fatal shooting, here is what News 6 has learned about the gunman from people who knew him and law enforcement officials.
[VIDEO BELOW: Neighbors of Fiamma gunman react to shooting]
Neumann was honorably discharged from the Army in 1999 and has no family in the Central Florida area, Orange County Sheriff Jerry Demings said.
The lone gunman's neighbor, Elizabeth, who declined to give her last name, said Neumann had anger issues.
"I knew he had an anger issue, but I never thought he was capable of doing what he did today," she told News 6.
Elizabeth said that before the shooting she thought her neighbor was a nice guy who just seemed like there was something always bothering him.
When Neumann was fired from Fiamma Inc., the RV accessory company on Forsyth Road, in April he wouldn't talk about it, Elizabeth said.
The Maitland resident was a sports fan, regularly posting photos on Facebook of himself at Orlando City soccer and Solar Bear games.
Neumann had some encounters with authorities, including a 2014 incident at Fiamma Inc. where the shooting took place, Demings said in a news conference. Neumann was accused of battering one of his coworkers, but no charges were filed in that case and the battery victim was not among the five people killed in Monday's shooting.
The victim accused Neumann of punching him in the back of the head and knocking him to the ground, according to the 2014 incident report. A witness told deputies that he saw Neumann and the employee arguing but did not see a physical fight. Neumann has left the scene and was not interviewed by deputies.
“In terms of his total motive for shooting the specific individuals involved, we have information that at least one of them he had a negative relationship with, but he was certainly singling out the individuals that he shot,” Demings said.
Neumann had a minor criminal history that includes marijuana possession, DUI and a misdemeanor battery charge, Demings said. Records from the Seminole County Sheriff's Office show that Neumann was arrested in 1995, 1996, 2000, 2003, 2009 and 2010.
During the 2003 arrest, deputies say that Neumann stole a license plate and put it on his beige 1981 Toyota pickup truck, which was not registered. The truck was found parked outside an Altamonte Springs home with the passenger side door left wide open.
Nuemann had a gold, metal marijuana pipe in his pocket when he was arrested. He was charged with possession of stolen property, marijuana possession, paraphernalia possession and driving with a suspended license as a habitual offender.
Concerned that something might have been stolen, the deputy knocked on the door of the home and asked to speak to whomever owns the truck. Neumann told the deputy that vehicle had not been burglarized then invoked his right to remain silent when the deputy asked about the truck's registration, according to the arrest report.
Neumann Jr. was arrested in 1995 in an Orlando suburb for driving under the influence. He was arrested in 1999 for driving with a suspended license, theft, giving a deputy a false name and probation violation.
The next year, he was arrested for driving with a suspended license. In 2009, he was arrested for marijuana possession, driving with a suspended license and leaving the scene of an accident in a hit-and-run where there was property damage
Demings described Neumann as a disgruntled employee, adding that the "tragic incident" is an example of workplace violence, and there's no indication of any ties to terrorism. He said Neumann was a "lone gunman."
Neumann did not have a concealed weapons permit, deputies said.
“In situations like this, my experience tells me that this individual made a deliberate thought to do what he did today," Demings said. "He had a plan of action, and he executed his plan today.”
The five victims were identified by authorities as Robert Snyder, 69, Brenda Motanez-Crespo, 44, Kevin Clark, 53, Jeffrey Roberts, 57, and Kevin Lawson, 46. Read more about them here.
The Associated Press contributed to this report.