SAN FRANCISCO — A 21-year-old Lodi man was released from jail Friday night after the San Francisco District Attorney said investigators had not yet gathered enough evidence to charge him in a fatal stabbing that left a Dodgers fan dead near AT&T Park Wednesday night.

A jail official said that Michael Montgomery was released from police custody around 9 p.m. Friday.. Hours earlier, District Attorney George Gascon released a statement saying that investigators had not yet interviewed all the witnesses to the fatal stabbing of 24-year-old Fort Bragg resident Jonathan Denver.

San Francisco police Chief Greg Suhr said Thursday that Montgomery made some “incriminating statements” during interviews with investigators that led to his arrest.

However, in an interview with a Lodi newspaper Thursday, Montgomery’s father said that his son had told him that he had acted in self-defense.

The father said 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. That’s when Denver and others hit his son and their friends without warning, Marty Montgomery told the Lodi News-Sentinel.

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.'”

The father did not address why his son had a knife or where the chair came from.

Police also detained an 18-year-old man in connection with the killing but released him Thursday after additional witnesses came forward, a San Francisco police spokeswoman said Friday. Police continue to search for two others who may have been present during the incident, 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.

Gascon said police haveprovided his office with an initial investigation report, but prosecutors are still hoping to hear from more witnesses, including anyone who was at the scene but not involved in the fight.

Gascon said the issue of self-defense could be very significant in his decision. “If there is evidence that points out to self-defense, then the case would not be charged,” Gascon said. “We do not know yet. We have not seen the evidence.”

Denver’s grandparents, Robert Preece Sr. and Anne Marie Preece, said their grandson, his brother and his father, Robert Preece, attended the game to celebrate the father’s 49th birthday. Robert Preece lives in Southern California and works as a security officer on game days at Dodger Stadium.

“They had a great time at the game sending pictures to family and friends throughout the evening,” a family statement said. “As we understand it, after the game they walked a few blocks from the stadium for a birthday drink.”

The statement said that the elder Preeces have not talked to their son about the incident and don’t know what later ensued, “only that everything went bad very quickly.”

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.

Both Marty Montgomery and the suspect’s mother, Victoria Montgomery, have not returned multiple calls from this newspaper and requests for comment.

Denver, a plumber’s apprentice, was described by those who knew him as “very mild-mannered.”

“He was an amazing guy who made everybody happy and made them laugh. He was there for everybody,” said his friend, Matt Gomes.

Denver’s grandparents said the killing demonstrates how society’s values have deteriorated over time.

“There is a loss of respect for human life, of family values, honesty and of the benefit of differing opinions,” they said in the statement.

“Jonathan was a gentle, kindhearted soul who loved his brother and his family very much. He was just starting his adult life. Jon was our grandson, a son to Robert, a nephew to our five daughters, a cousin to many, and an uncle. We all loved him very much. Jon was always smiling, and that is how we will forever remember him.”

The stabbing came during a week when the Giants are holding three fundraisers for Bryan Stow — the Bay Area Giants fan who suffered brain damage after being beaten following the 2011 season opener in Los Angeles.

Stow, a Northern California paramedic, suffered a traumatic brain injury when two men dressed in Dodgers gear attacked him after the teams’ March 31, 2011, game at Dodger Stadium. The two are awaiting trial on charges in the beating, which sparked outrage and brought stadium security changes around the state and country.

Stow’s family said in a statement Thursday that they were “horrified and deeply saddened” by Wednesday’s violence. “Our thoughts and prayers go out to the family.”

Staff writer Katie Nelson and wire services contributed to this report.