They want police dash camera video released to the public – video that Grapevine police say shows the suspect not following the officer's orders.
The entire incident was captured on dash cam video, but the shooting occurred off-camera.
Everyone involved agrees that the man killed, Ruben Garcia, was unarmed, but among those who've seen the video, there are very different interpretations about what led up to it.
Last Friday evening, Officer Robert Clark tried to pull over Garcia for a traffic violation.
There was a short chase that ended on the Hwy. 121 service road in Euless.
One passing motorist recorded cell phone video before the shooting that shows Officer Clark with his weapon drawn.
Grapevine police say Garcia had put his hands on his head, but refused to comply with Officer Clark's demand to halt and kept advancing on him.
Garcia was shot twice outside the view of the dash camera.
Hispanic activist Carlos Quintanilla with Accion America has seen the video, and he says anyone who sees it will be shocked by what happened.
"When the officer said, ‘Don't move, [expletive]!' Ruben stayed there, and for one reason or another, Ruben begins to walk toward the police officer and not one second passed and the officer fired twice," said Quintanilla. "Pop! Pop! And Ruben was dead."
The family's attorney is calling for a state and federal investigation and for the immediate public release of the dash cam video.
"When this video is released, it will show that a man with no prior criminal record, a wife and four children who puts his hands on his head and is shot twice ‘cause he asked the officer to treat him with respect and dignity and not to be calling him mother-‘F' multiple times," said Domingo Garcia, the family's attorney.
Police say they are limited in what details they can release from the investigation, and they say releasing the dash cam right now could taint the possible witnesses they're pursuing.
"We have other witnesses that have not come forward and are posting stuff on social media," said Lt. Eric Starnes with the Euless Police Department. "What we don't want to be, as a police department, is to be a source of witness contamination. So until we reach all of the witnesses down, we are withholding that video until we can complete our investigation."
FOX 4 could find no previous criminal record for Ruben Garcia. His family says he was a mechanic and hardworking man who'd worked for the same company for the last 12 years.