Three weeks before Micah Xavier Johnson opened fire on Dallas police, he offered to work security for protesters outside a Donald Trump appearance in Dallas. Organizers said “no way” – because Johnson wanted to bring a gun.

Rev. Peter Johnson is a longtime Dallas civil rights activist – and no relation to the suspected shooter. Johnson has led marches for decades, going back to his years with Martin Luther King Jr. He’s lived by King’s ethos of non-violence.

Johnson was helping plan the June rally against the presumptive Republican presidential nominee when a man named Micah Xavier Johnson appeared.

“Young man comes and says 'I’m going to participate, I want to help, but I want to bring my gun,'” Johnson recalls. “I say 'Hell no; you can’t bring your gun.' That’s all I remember about him. I told him you can’t bring your gun to a protest that I’m involved in.”

Through the years, Johnson has seen death and violence visited on friends and colleagues by people using guns.

“This pathologic affair that America has with guns, we’re the laughing stock of the world because of this," Johnson says.

At the march against Trump, one man was arrested, another hit by a thrown rock. Otherwise, the protest was peaceful. So was Thursday’s march through downtown Dallas, until Micah Johnson appeared.