New information has come out about the mass shooter who seriously wounded three people at his place of employment, and who was ultimately shot and killed by police, in Middleton, Wis. on Wednesday.

According to a report from the Miluawakee Journal Sentinel, the shooter, whose name will not appear in this article, has a history of mental health issues. While living in South Dakota in 2004, Sioux Falls police visited the man, where they found him to be “delusional” and “paranoid.” The shooter at the time was armed and had dismantled fire alarms in his home because he thought his neighbors were listening to him.

Here’s more from the Miluawakee Journal Sentinel.

Sioux Falls Police Department officers were called to [the shooter’s] apartment building in August 2004 after an alarm company alerted his landlord that [he] had disabled a fire alarm in his apartment, according to Minnehaha County, South Dakota Sheriff’s Department records.

Police found [he] had disabled smoke alarms, ceiling lights, ceiling fans and anything attached to a wall or ceiling that was powered by electricity. [The shooter] said he had disabled everything because “people in the apartment below him were eavesdropping on him.”

Police said [the shooter] was acting defensive, delusional and paranoid, and was carrying a loaded handgun with a double magazine, pepper spray and two knives. Police also found a Colt AR-15 rifle in the apartment and a large amount of ammunition.

Years later, in March of 2017, the shooter reportedly moved to Wisconsin.

Middleton Police Chief Charles Foulke told the Miluawakee Journal Sentinel that a federally licensed firearms dealer would know about the revocation of the shooter’s gun permit, but also said he wasn’t sure if the incident in 2004 “involved [the shooter’s] workplace and whether the incident would show up on a criminal background check.”

Reports are also stating that police are having a difficult time tracing the firearm the shooter used because the gun is “unique.”

Though this information provides more background on the shooter, the police chief is cautioning people not to jump to conclusions.

The Miluawakee Journal Sentinel reports Foulke as saying:

We must use caution in trying to jump to conclusions that this is a mental health shooting-related incident. And also we need to be cautious that we don’t paint everyone with a broad brush of everyone with a mental health issue is going to become an active shooter because as we know, that is not the case and that is not at all what we are trying to push out today.

…

He came to work that day and was working on a normal basis when this happened.

The shooting in Wisconsin hasn’t received the typical wall-to-wall coverage other mass shootings have gotten, but these developments may push it back into the spotlight as lawmakers, at the state and federal level, will have to wonder how gun laws failed to keep a firearm out of the hands of someone prohibited from owning one.