A lawyer for the family of 29-year-old Christopher Harris said the video and witness accounts show the Edmonds restaurant worker was a victim of excessive force by Deputy Matthew Paul, 26.
As of late Thursday, Harris remained comatose and in critical condition at Harborview Medical Center, said Todd Keeling, his stepfather.
Sheriff's Sgt. John Urquhart, who released surveillance video of the May 10 episode, said a preliminary investigation by the sheriff's office showed there was probable cause to arrest Harris because he fled from two deputies who repeatedly identified themselves as police.
The crucial videotape shows the end of the chase as moviegoers are exiting from the Cinerama theater, about 2½ blocks from where the chase began.
Harris comes into view, makes a slight turn and slows down as Paul gives him a fierce shove, knocking him off his feet. Harris' head slams into the base of a tiled wall outside the movie house.
Two witnesses say Harris seemed to be stopping and said, "I don't have anything, I didn't steal anything," just before he was hit by Paul, who weighs about 270 pounds, about 100 pounds more than Harris, family lawyer Simeon Osborn said.
Paul and Deputy Joseph Eshom, 28, were on foot patrol as Metro Transit police, wearing dark uniforms in a dimly lit area.
The reason Harris ran after Paul and Eshom told him to stop remains unknown. Days after the chase, investigators determined he had nothing to do with the earlier commotion.
Paul could have used a stun gun or other less forceful means to stop Harris, Osborn said.
"We believe that the actions by Deputy Paul were horribly brutal at best and criminal at worst," the lawyer said. "That wasn't a tackle, it wasn't a push ... it was a hit like a linebacker would make on the sideline."
Eshom has returned to work. Paul remains on paid leave but could return at any time, Urquhart said.
"Our preliminary conclusion is that our deputy didn't break any laws in the use of force," he said. "The fact that he (Harris) was injured was a tragic accident."
A second, internal investigation to determine whether Paul followed sheriff's office policies on the use of force may begin soon and could take weeks to complete, Urquhart said.
Osborn said the family would likely wait until that probe is completed before deciding whether to file a damage claim that could lead to a lawsuit.
Sheriff Sue Rahr has asked Seattle police to review her department's completed investigation.
The sheriff's investigation findings will be forwarded to the King County prosecutor's office to make a final determination on whether any criminal charges should be filed.