Orlando, FL – The man who took four children hostage and then murdered them all during a 21-hour standoff with police on Monday should not have had guns, and should have been in jail.

The tragic incident began at 11:45 p.m. on Sunday, when a woman fled from her apartment and called police from a nearby store to report that she had been battered by her boyfriend, 35-year-old Gary Wayne Lindsey Jr.

She told police that Lindsey had all four of her children – two of whom were also his – in the apartment with him.

When police attempted to get into the apartment, Lindsey was waiting on the other side and fired through the door, shooting Orlando Police Officer Kevin Valencia in the eye, WFTV reported.

A standoff lasted for almost 21 hours, as police attempted to negotiate with Lindsey and secure a safe release for the children.

Orlando Police Chief John Mina announced at a press conference just before midnight on Monday night that SWAT officers had entered the apartment and found that all four children and the suspect were dead from gunshot wounds.

Police said Lindsey, a convicted felon, was found to have been in possession of two rifles, two shotguns, and two handguns, all of which he was believed to have inherited from his father, USA Today reported. He was prohibited by law from possessing firearms because of his violent felony convictions.

Court documents showed that Lindsey was on probation at the time of the standoff for an incident that occurred in Volusia County in December of 2008.

In May, Lindsey violated his probation by committing a retail theft, and was arrested, USA Today reported.

At that time, a probation officer recommended that Lindsey be sentenced to six months in jail, but the judge gave him supervised probation instead, even though he was already on probation, and ordered him to pay restitution, court records showed.

Less than a month later, Lindsey had murdered four children, critically wounded a police officer, and taken his own life.

Lindsey had been sentenced to 35 years of probation in 2009, after he pleaded no contest to charges of fleeing or attempting to elude a law enforcement officer and arson for setting fire to a home after an argument with his girlfriend, WFTV reported.

During the altercation, Lindsey grabbed a knife and stabbed the woman’s television, then proceeded to punch the TV with his fists, Heavy reported.

“You need to get the dogs and leave my grave,” he told the woman, according to an affidavit obtained by the Orlando Sentinel.

When she tried to call police, Lindsey broke her phone.

After she fled the residence, Lindsey poured gasoline throughout the home, then set it ablaze.

Lindsey was repeatedly arrested for violations of his probation, to include a 2012 arrest for aggravated battery and aggravated assault stemming from a physical altercation with another woman, WFTV reported.

During that incident, Lindsey allegedly held a knife to the throat of his girlfriend as she was holding their infant son, and threatened to kill her, Heavy reported.

He ultimately dragged her to another room, causing her to drop their baby onto the ground.

The child was not injured, but the woman sustained a cut to her hand as she struggled with Lindsey, Heavy reported.

She ultimately escaped and contacted police, who found her covered in blood.

Lindsey was released from custody after prosecutors failed to file the new charges within 30 days, WFTV reported.