"My father was, like, an icon in the boxing world," said Steve Harris, the suspect's uncle. "Everybody knew him -- all across the world."
He said he and his family almost expected something bad to happen because Lucien Harris had untreated mental health issues.
"It's not a complete surprise. Not to me," Steve Harris said. "It could have been me. It could have been my other brother in the car, my sister. We all knew something was going to happen eventually, but not my dad."
Lou Harris owned Harris Boxing on Ivey Lane in Orlando and trained hundreds of fighters, including his grandson, relatives said.
"He took people from the street and took them right to the Olympics -- and (they won) gold medals, bronze medals. He did it all," Steve Harris said of his father.
He said Lucien Harris was living with his grandfather at his Florence Vista Boulevard home. He said Lucien Harris was once a boxer, too, but was not successful and was resentful and jealous because of it.
Records said Lucien Harris was arrested in October after he was accused of threatening to kill his uncle with a hammer and knife.
His uncle told investigators at the time that Lucien Harris has "schizophrenia and bipolar disorder and does not take medications for his issues," records said.
Lucien Harris was not prosecuted in that case.
Records said his arrest history dates back to 2004, when he was arrested on charges of assault with a deadly weapon.
Since then, he has also been arrested on charges of possessing a gun as a convicted felon, armed burglary and grand theft.
"His grandson had issues for many years," Steve Harris said. "He did time at an early age."
Lucien Harris was arrested and charged with first-degree murder.