The West Palm Beach city spokesman says Douglas Ellington was on their radar, but there was no indication he would target the city's sewage plant.
Ellington was arrested on Monday after investigators say he drove his SUV into the sewage plant off Haverhill Road and then set it on fire.
City spokesman Elliot Cohen says there was also an indication that an explosive could be somewhere else at the plant.
That explosive turned out to be fake, and bomb threats in Riviera Beach connected to the incident also turned up no real explosives.
Ellington was fired by the city of West Palm Beach and then went on to work for Riviera Beach until he was fired there earlier this year.
"The police have been involved in this since the beginning. As far as when he was dismissed, fired in 2011, and soon after that if he started sending emails, all those emails are sent over to the police department," Cohen said.
On top of sending emails to city leaders, Ellington has also gotten into trouble at city hall in the past.
In August of 2015 he was arrested when he ran past security to get to the mayor's office.
And he was arrested earlier this month when he refused to leave a city commission meeting.
After his first arrest, he told News Channel 5 that he was emotional because he thought he was being punished by city leaders for telling them about safety concerns at the sewage plant.
"What was going through my mind is someone is going to look at me from this commission and from the city administration," Ellington said.
In light of the incident, Elliot Cohen says the city is investigating security protocol at the sewage plant.
There is a security guard outside the plant, but the gate to enter the plant was open most of the day Monday while crews appeared to be working on its motor.
Cohen says security at city hall was aware of Ellington, but they didn't think he would target the sewage plant.
"City Hall security was well aware of him. Up until this point all of his contact was with people at city hall. So we did not put out any kind of a....we have hundreds of properties so there was no indication if would involve the sewage plant," Cohen said.
According to court records, Ellington was never arrested or in trouble with the law until he was fired by the city of West Palm Beach.
City administrator Jeff Green says they've tried meeting with Ellington before. Green says Ellington was ultimately let go because he didn't show up to a disciplinary hearing.