A family member said the victim's father, Robert Preece, plans to speak outside the Giants' stadium before the scheduled 1:05 p.m. PDT Sunday game with the San Diego Padres.
Lodi resident Michael Montgomery, 21, was released from jail Friday night after the San Francisco district attorney said police had insufficient evidence to charge him in the death of Jonathan Denver.
The district attorney said police had not spoken with any independent witnesses who may have witnessed the fight Wednesday night. Denver's father believes someone may have recorded the melee with mobile phones, said Preece's sister Jill Preece Haro.
"We have reason to believe someone recorded this," Haro said in a phone interview, adding that Denver's father and others with him saw bystanders were using cellphone cameras. "We're calling on them to come forward to help both families find out what happened."
Haro said the victim's father, who works as security guard at Dodger Stadium, and other family members were motivated to travel from his Southern California home to make his public plea after Montgomery's release and Gascon's explanation for not charging Montgomery.
Police believe Montgomery stabbed 24-year-old Jonathan Denver of Fort Bragg after Wednesday's game.
They say the two got into an argument over the Dodgers and Giants just a few blocks from AT&T Park.
Denver was with his father, brother, and two other people.
A fight started and Denver was killed.
His aunt Janet Alvarado, who lives in Southern California, can't understand how this happened.
Janet: "All I know is that they were walking back to their vehicle, to get into their vehicle, a Giants fan made a comment, comments were exchanged, and an altercation broke out."
Reporter: "You said your brother's not the kind that would want to fight back?"
Janet: "No, none of them were fighters. I wish I could tell you how this happened, why this happened. I have no clue why anyone would do this to any family."
Montgomery's father told the Lodi News-Sentinel that his son was jumped during the fight, and he stabbed Denver in self-defense after Denver and others yelled "Giants suck." The father told the News-Sentinel that his son alleged Denver hit him over the head with a chair during the fight a few blocks from the stadium.
A second suspect was questioned and released by police Friday. Two others were being sought.
The death of Denver, who worked as a plumber's apprentice for North Coast Plumbing, Heating & Sheet Metal Inc. in Fort Bragg, is the latest violent incident to mar the Giants-Dodgers rivalry.
Two years ago, Giants fan Bryan Stow suffered permanent brain damage when he was attacked in Los Angeles. Two people have been charged in that beating and are awaiting trial.
There was a moment of silence for Denver before the Dodgers hosted the Colorado Rockies on Friday night.
"I just can't understand how, sporting event aside, society's gotten like this," Giants general manager Brian Sabean said Friday. "It's bizarre to me."
Officials say that anyone with video of the incidents leading up to Wednesday night's stabbing should contact police immediately.
(Bay City News and the Associated Press contributed to this report)