Family members of David Ordaz held a march and rally for justice on Saturday.
The 34-year-old East LA resident was shot and killed by Los Angeles County Sheriff's Department deputies.
Bodycam video captured the deadly March 14 encounter outside the family's home.
Ordaz was seen holding a knife as deputies pointed guns at him.
His sister says she called authorities because her brother was having a mental-health crisis.
"I had called myself for guidance and help for him," said Hilda Pedroza, his sister. "I needed help because he was trying to commit suicide."
Family members witnessed the fatal shooting.
Although Ordaz, a father of three, was armed they say they don't understand why the deputies opened fire.
"He did have it out all the time, it was pointing down," Pedroza said. "It was never aimed at anybody throughout the whole entire time."
Sheriff Alex Villanueva has expressed "grave concerns" about the shooting. In July, the sheriff said one of the four deputies involved was relieved of duty.
Sheriff Villanueva expresses 'grave concerns' over deadly shooting by deputies caught on bodycam
The family is suing the sheriff's department and the deputies. They'd like to see mental health professionals, not officers or deputies, brought in to handle such situations.
"He was important to us," Pedroza said. "He wasn't just anybody. He was our brother, our son, our father."