Thomas' family took aim at the L.A. County Sheriff's Department, saying 21-year-old Robert Thomas Jr. was shot in the back a dozen times.
"They killed my son," said the suspect's father, Robert Thomas Sr.
The deadly deputy-involved shooting happened in the area of East 123rd Street near Wilmington Avenue just after 10:15 p.m. on Monday. Deputies were patrolling the area where a party was going on when they said they saw a group acting suspiciously.
When deputies tried to talk to Thomas, he would not cooperate and then fled on foot, running from deputies, according to L.A. County Sheriff's Lt. Dave Dolson.
"Regardless of what he ran for, you have no right to shoot me in the back 12 times," said Willie Williamson, a friend of the Thomas family.
His family knew him as reliable security guard contracted by Home Depot .
"He was 21 years old and he worked every day," said Thomas Sr. "This was his off day. He got killed on his off day."
But L.A. County Sheriff's Dept. investigators knew him for another reason.
"I do know that he is, or was, a local area gang member," said L.A. County Sheriff's Lieutenant Dave Dolson.
Deputies say they were patrolling in Willowbrook Monday night when they saw a crowd of people and Thomas acting suspiciously. They approached. Thomas fled on foot.
"He ran out this way and he started running across the street, and by the time he got right here, the police were right there about half the distance from his back. They could have just pushed him over and told him, 'Don't move,'" said Williamson. "But by the time he got to the corner, everybody couldn't see him anymore. Police just started shooting."
What observers didn't see?
"At that point, the individual turned toward one of our deputies, deputy saw that he was armed and the deputy fired multiple rounds at this suspect," said Dolson.
Thomas's sister was taken into custody shortly after the shooting for being unruly and resisting arrest.
"They're lying, basically, saying that my son pulled a gun on them. But you can't pull a gun with your back turned from them and get shot 12 times in the back," said Thomas Sr.
"As far as where the suspect was shot, that will be understood after the autopsy is complete," said Dolson.
"They said they feared for their life. That kids was no threat to nobody," said Williamson.
Yet deputies report they recovered a loaded weapon. They are not revealing at this time what suspicions led them to Thomas in the first place.
Asked if the deputy knew if Thomas was a gang member before he shot him, Dolson answered, "I don't know that information at this time."
The investigation continues. Autopsy results are expected within days.