A 21-year-old San Francisco Giants fan arrested on suspicion of stabbing a rival Los Angeles Dodgers fan walked out of jail Friday night due to a lack of evidence, leaving San Francisco prosecutors with a year to file murder charges against him.

Michael Montgomery, of Lodi, was released from jail at 9:04 p.m. -- about 48 hours after the Wednesday night attack that followed a Giants' win over the rival Dodgers -- as the San Francisco district attorney asked for witnesses to come forward with videotape or recollections of the fatal stabbing of Jonathan Denver, 24, of Fort Bragg.

Denver's father plans to address the media before the Giants' Sunday season finale outside AT&T Park and ask for witnesses to come forward.

"My office extends its deepest and most heartfelt condolences to Jonathan Denver's family," said San Francisco District Attorney George Gascon in a statement Friday before Montgomery was released. "We are extremely concerned about the loss of life and want to make sure justice is served.

"Additionally, in California, it is the People's burden to prove beyond a reasonable doubt that the defendant did not act in lawful self-defense," he continued. "It is vital for our office to have independent corroboration of the incident in order to meet our ethical obligation to charge this case."

Montgomery's father told a Lodi newspaper that his son acted in self-defense.

The Lodi man's arrest came after he made an "incriminating statement" during interviews with investigators, said San Francisco police Chief Greg Suhr.

Neither Michael Montgomery nor his parents were available for comment Saturday.

The father, Marty Montgomery, told the newspaper that his son told him in a phone call made while in police custody that Denver, wearing Dodgers apparel, yelled "Giants suck!" at Michael Montgomery's friend, who was wearing a San Francisco Giants hat. Denver and others then hit his son and their friends without warning, Marty Montgomery told the paper.

During the fight, the father said, Denver hit his son over the head with a chair, and, in self-defense, his son stabbed Denver.

"He's freaking out," Marty Montgomery, 47, told the Lodi newspaper. "He's like, 'I saw him die in his dad's arms.'"

Denver's father, Robert Preece, attended the baseball game with Denver and his other son, Robert, 26, and the death has taken a particular toll on the brother.

"His brother is going to be lost without him," said his ex-stepmother Staci Preece-Wojdak, a Pasadena woman who helped raise Denver since he was 3. "They were immensely close. They were a package deal."

Preece-Wojdak, 46, called Denver a "sweet, gentle young man who kept to himself."

"He would protect his family to a fault," she said. "That was the only time you heard from him."

She said the brothers were living together in Fort Bragg, working and trying to start a life. Baseball was a common thread for the young men, with Robert being the more passionate of the two for the game. The brothers have been going to Dodger games since they were children.

Denver attended the Giants game Wednesday night with his father, brother and two others. Wearing Dodgers apparel, Denver left the ballpark with the group around 10 p.m. -- the eighth inning -- and was headed to a bar.

About 11:30 p.m., near Third and Stillman streets, they encountered another group of people -- one of whom was wearing a Giants cap -- that had been at a bar and not the game. There was "some back and forth about the Giants-Dodgers rivalry," police said, starting a fight.

That melee broke up, but when they crossed paths again minutes later at Third and Perry streets, a second altercation ensued, and Denver was stabbed. He was rushed to San Francisco General Hospital, where he died.

Police continue to search for two others who may have been present during the fight but have not released their names or information on their possible involvement in the killing. Police are also looking for the weapon used in the stabbing. Police detained an 18-year-old man in connection with the killing but released him Thursday.

"Not all witnesses have been interviewed, nor have any independent witnesses of the incident been interviewed," Gascon said. "We have requested this and other evidence be collected before we can make an assessment on whether charges should be filed."

Staff writer Katie Nelson contributed to this report.