CHICAGO (CBS) — The man who killed an emergency room doctor, a pharmacy resident, and a Chicago police officer at Mercy Hospital on Monday had been fired from the Chicago Fire Academy in 2014,  after he went AWOL while  facing disciplinary action for inappropriate conduct with female cadets.

The Chicago Fire Department confirmed Juan Lopez started training as a firefighter candidate in March 2014. While in training, he was accused of bullying, including “inappropriate contact with fellow female cadets.”

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Fire Department spokesman Larry Langford said, after the department launched disciplinary proceedings, Lopez went absent without leave. Officials tried to contact him, but he never responded, so he was fired in May 2014 for going AWOL.

At the end of 2014, Lopez’s wife at the time took out an order of protection against him, claiming she feared for her safety, because he had started sleeping with a gun, and leaving it accessible to their child. She also accused him of pulling a gun on a realtor during an apartment appraisal, and going after a neighbor with a gun.

His wife at the time filed for divorce months later.

Most recently, Lopez worked for the Chicago Housing Authority, and was attending graduate school at DePaul University, majoring in policy.

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Lopez had been employed since February as an associate program specialist for the customer care center at CHA headquarters.

CHA officials said he passed a background check, and had no history of complaints while he worked for the agency.

“This was an unthinkable act of violence. We are filled with overwhelming sadness and our hearts go out to the families of those who died, and to all affected by this horrific tragedy,” CHA chief executive officer Eugene Jones Jr. stated in an email.

Lopez also held a valid Firearm Owner’s Identification Card, and a license to carry a concealed weapon.

Here’s what else we know about Lopez:

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• Lopez, 32, shot and killed his former fiancée, Dr. Tamara O’Neal, in the parking lot outside Mercy Hospital and Medical Center, after the two were seen arguing outside.
• He fired at police officers responding to the shooting, damaging a squad car, before entering the hospital.
• He shot and killed 24-year-old Dayna Less, a pharmacy resident at Mercy, as she exited an elevator.
• He shot and killed Chicago Police Officer Samuel Jimenez, one of the officers who confronted him inside the hospital.
• He was shot and killed inside the hospital. Police have said it’s unclear if he shot himself, or if he was shot by the SWAT team.