The homeowner, his wife, son and grandson were in the home when the intruder broke in just after 5 a.m. in the 600-block of North Sawyer.
The homeowner is said to be shaken that he killed a man but confident he did the right thing. The armed intruder was on parole and has a history of drug arrests and gun convictions going back more than a decade.
Police believe the would-be robber rode his bicycle to the elderly couple's home and entered through a back window. Inside, he encountered an 80-year-old veteran of the Korean War, armed with the intent to protect his family.
"It's gonna be them or us when you come into our house," said Butch Gant, homeowner's son.Gant was staying at his parent's place when he heard his mother scream. He says the intruder first fired at his parents. His dad fired back, killing the intruder who was in his 30s.
"I feel sorry for them, you know, that they have the loss of their family members but it's either them or us. That's what I say and that's what my father say," said Gant. "He did what he had to do to protect his family. That's the main thing: Protect your family."
Also home during the pre-dawn break-in were several family members including the homeowner's 12-year-old grandson. His mother, the homeowner's granddaughter, talked to ABC7 but asked not to reveal her identity.
"He's a little bit in shock but he's brave. He's cooperating with police also," said the woman. "My thoughts are you have to protect your belongings and your family and at their age what else are they going to do?"
In the East Garfield Park neighborhood, plenty of people are now calling the homeowner a hero.
"They're 80-something years old. Why would somebody go in their house? I'm 75 and I know what I would do," said Audrey Williams, neighbor.
"I would so the same thing, too, to protect my life, and my mom's life. You got to," said Jose Perez, neighbor.
Relatives say the homeowner bought a gun just a few months after an even more brazen robbery last November, where the crooks stole $100.
"Three guys came in and robbed him, same demo through the back," said Gant. "He said, 'it's not going to happen again.'"
Police interviewed the homeowner for several hours, then released him without charges. Owning a gun in the city is illegal, but so far the homeowner hasn't received a citation.
Chicago's ban on hand-guns is now before the United States Supreme Court. Opponents of the ban have long argued it violates people's constitutional right to protect themselves.
"People want to defend their homes against people who have illegal weapons already. And they have illegal weapons regardless of a handgun ban," said David Sigale, anti-gun ban attorney.
The elderly couple's relatives and neighbors say this case is proof a gun in the right hands can potentially save lives.
"Anytime anybody come in your house you supposed to kill 'em. If somebody came in my house I know what I'm gonna do," said Williams.