A judge ruled today a Peninsula teen accused in the one-punch death of another teen during a fight outside San Francisco’s AT&T Park in 2008 should stand trial for involuntary manslaughter.Taylor Buckley, 19, of San Carlos, is alleged to have punched Anthony Giraudo, 18, of Redwood City, during an argument outside the stadium at about 9:45 p.m. on May 9, 2008, near the end of a San Francisco Giants game. Both men had reportedly been drinking that night. Giraudo, a baseball player who had been attending Canada College in Redwood City, fell and struck his head on the pavement and was knocked unconscious. He was pronounced dead at the hospital the next day.Prosecutors contend Buckley sucker-punched him once on the side of the face with a closed fist. They did not charge Buckley with murder because the killing was deemed not to have occurred with malice.Buckley’s attorney Douglas Horngrad has said his client did not intend to kill Giraudo and has called the incident “a tragic accident.” He said Buckley is remorseful and devastated about what happened. Testimony at a preliminary hearing in the case today included the accounts of a witness to the attack, a police inspector and a medical examiner.The witness, Hector Pena Lora, testified that as he and his friends walked out of the stadium, one of his friends said, “Oh my God. They’re going to fight.”Pena Lora said he looked up and saw a group of eight to 10 people arguing from as much as 80 feet away. He said he then saw a man wearing a white hooded sweatshirt — who he identified in court as Buckley — throw an overhead, downward-swinging punch at Giraudo.Giraudo was standing behind two women who seemed to be trying to separate those arguing, and he had his arms down at the time he was struck, according to Pena Lora.Giraudo was struck on the left side of the head and “went straight to the floor,” Pena Lora said.”His head bounced off the ground,” Pena Lora said.After the punch connected, Buckley “smiled and puffed his chest,” Pena Lora said, but then, when Giraudo remained on the ground, Buckley showed a look of concern and began walking away with two of his friends. Pena Lora said he followed them and when he saw Buckley take off his white sweatshirt and drop it nearby, he went to confront him and was called “a snitch” by one of Buckley’s friends. Pena Lora pointed Buckley out to police and Buckley was arrested at the scene.Pena Lora acknowledged during cross-examination that he did not know what the argument had been about, or what transpired before Buckley’s punch. Police Inspector Gavin McEachern testified that Buckley told him during an interview that night that Giraudo had gotten into a verbal argument with one of Buckley’s friends and threatened Buckley’s group. According to McEachern, Buckley told him he had consumed three beers before the game but did not drink at the game.Buckley told McEachern he thought Giraudo was “stupid” for challenging them “three on one.”Buckley then admitted to punching Giraudo, saying he did so after his friend hit Giraudo with a glancing blow that had little or no effect.Buckley also admitted that his punch was “a cheap shot” and that Giraudo “could not see the punch coming,” McEachern said. After Giraudo went down, Buckley then began yelling, “Knockout! Knockout!” and dancing around, according to McEachern. He said he wanted to leave the area before police arrived and removed his sweatshirt because people were already identifying him as the puncher.Assistant Medical Examiner Dr. Ellen Moffatt, who conducted Giraudo’s autopsy, testified that the cause of death was blunt force injury to the head, which caused internal hemorrhaging on his brain. She could not say whether the punch or the ground was more likely to have caused the fatal injury.Moffatt also conceded under cross-examination that it was “possible” Giraudo’s blood-alcohol level of 0.12 could have made him impaired enough to lose his balance. “It’s a classic case of involuntary manslaughter,” prosecutor Pam Pecora-Hansen argued to Judge Wallace Douglass. She called the attack “an absolute sucker-punch,” an unprovoked blow that caused the fall that resulted in Giraudo’s death, she said. Horngrad said Giraudo’s death was “tragic,” but he called into question the witness’s account as biased, arguing Pena Lora was angry at Buckley for what he perceived as Buckley not taking responsibility for the attack. Horngrad suggested Buckley may have been defending himself or his friends.”There’s absolutely no evidence he was defending anyone,” Pecora-Hansen responded. “By his own statement, it was a cheap shot.”Douglass held Buckley to answer on one count of involuntary manslaughter. He is due back in court Sept. 22 for arraignment and entry of plea.Buckley remains out of custody. If convicted of involuntary manslaughter, he could face up to four years in state prison.