The gunman who killed five people and wounded numerous others in a Friday attack on a manufacturing plant in Aurora, Illinois, had a previous felony conviction that should've prevented him from getting a gun license, according to the Chicago Tribune.

The killer had been employed by the Henry Pratt Company in Aurora. He found out Friday that he'd been fired from his job, and immediately started shooting coworkers, according to police.

On Monday, authorities admitted that he technically should've never had legal access to the firearm he used to commit the murders.

From the Tribune:

According to state records, Gary Martin applied for a firearm owner's identification card on Jan. 17, 2014. He provided his name and birth date for a background check, and falsely answered "no" when asked if he had ever been convicted of a felony.



A records search only returned Martin's criminal history in Illinois, a series of minor infractions that did not disqualify him from owning a gun. The screening process failed to detect a mid-1990s felony conviction for aggravated assault in Mississippi for which he served five years in prison and was released in 1997.



Martin received his gun license on Jan. 31, 2014. Less than five weeks later, he purchased a .40-caliber Smith & Wesson from an Aurora gun dealer. The purchase was approved March 6, 2014, after Martin's name and birth date cleared a second background check.

Illinois State Police became aware of the error as soon as the suspect submitted his fingerprints to speed up the concealed carry license application process. The department said it revoked his license within a month of that application, and sent a letter saying he was not legally allowed to own a gun.

He was supposed to then transfer the gun to law enforcement or to someone with a valid license and submit a firearm disposition record to the Aurora PD proving he no longer had the gun.

The issue here appears to be that it's unclear whether any of the involved agencies followed up on this process to make sure the suspect did not keep the gun. Aurora Police Chief Kristen Ziman said the department is now looking into how this situation was handled.