"They have the ability to do that as private citizens like everyone else," said Missouri Governor Mike Parson on Tuesday.
The man prosecutors called the "Parking Lot Vigilante" faces up to 30 years in prison for the 2018 shooting death of Markeis McGlockton.
"I'm the only person here of color, OK?" Senator Flowers said. "I am a mother too. And I have a son. And I care as much for my son as y'all care for yours. But my son doesn't walk the same path as yours does. So this debate deserves more time."
Markeis McGlockton, 28, was shot to death in front of his 5-year-old son. The shooter will not be arrested or charged.
While lawmakers across the country have introduced gun control legislation since the Parkland shooting, some states are passing laws to protect the Second Amendment.
Keller told a crowd of gun rights activists that the Marjory Stoneman Douglas High School survivors should be written off because they were "eating Doritos and playing video games" before the mass shooting.
The Florida House passed a bill that would force the state to prove a shooter acted unlawfully before it brings a case to trial.