San Francisco- It looked for all the world as if the couple on a date — he was darkly handsome and a little older than the pretty, petite blonde with the Russian accent — were having a great time together.

“A really great time,” their waitress, Karri Cormican, recalled thinking. “She was facing him, had one of her legs up on the bench seat.” Good body language.

So it came as a shock when after the woman left the window-side table to visit the restroom, Cormican saw the man shake a white powder into the Hefeweizen beer he had ordered for his date.

“Did I really see that?” Cormican asked herself. “Why would he do that? It seemed like they were having fun.”

This was in a bar in Noe Valley that draws a mostly local crowd — early on most days, the patrons were older folks like the 93-year-old who got upset when the bar manager took a week off. Later, when the restaurants on 24th Street close for the night, a younger bunch of waitstaff and kitchen workers dropped in to watch sports on television or play pinball.

Over the years, the bar has seen a lot of incarnations. When the neighborhood was mostly blue-collar Irish and German, it was Doyle’s, and then it became the Connection. As yuppies moved into what became million-dollar Victorians in the 1990s, it became Noe’s Arc, and now it’s Noe’s Bar.

Not a place for trouble. Not the kind of place where what looked like an attempted date rape would occur. Or where a guy on a first date, like Joseph Szlamnik, at the time a 43- year-old senior management assistant for the San Francisco Unified School District, would commit a crime. Szlamnik was sentenced last week to a year in jail by Superior Court Judge Anne Bouliane on narcotic charges related to the incident.

According to the National Crime Victimization Survey conducted by the Department of Justice, 66 percent of sexual assaults in 2005 were committed by friends, acquaintances or other people intimately known to the victims. No tally is kept specifically of date rapes.

Rape of all kinds has dropped by more than half since 1993, said Lynn Parrish, a spokeswoman for the Rape, Abuse and Incest National Network, which operates a national hot line.

Because of educational efforts, “people are aware that these drugs are used in bars by perpetrators of all ages,” she said. “So these two women who saw it knew what was happening.” On the night in question, Cormican, 23, quickly approached the bartender, Hannah Bridgeman-Oxley, 27, and told her what she had seen. The two women hatched a plan.

Cormican returned to the table and told Szlamnik and his date, whom the court identified only as Tatiana K., then 34, that the woman’s beer had come from a fermented keg and that they were going to replace it. Cormican brought her a Stella Artois.

Cormican carried the adulterated Hefeweizen to Bridgeman-Oxley and out of sight into a back room. They held it up to the light and saw, unmistakably, a white powder. At a preliminary hearing last summer, Nikolas Lemos, chief forensic toxicologist at the San Francisco medical examiner’s office, identified the powder as zalepron, a prescription sleeping drug sold as Sonata.

After seeing the white powder, Bridgeman-Oxley said she “panicked a little bit. We had to figure out a way to keep her away from this man.”

Their chance came when Tatiana went outside to smoke a cigarette. Cormican grabbed the beer with the white powder and followed her. It was a mild night in May 2005 — the wheels of justice in this case, as one courtroom observer said, have ground exceedingly slowly.

Tatiana was stunned — she said it was their first date, and they had met at a salsa dancing class only weeks before. Earlier, he had picked her up in his BMW after her classes at City College. “She’s a trusting young lady,” says David Merin, the assistant district attorney who prosecuted the case.

Cormican had to repeat herself several times before Tatiana absorbed what had happened. And then things got even worse.

The bartender rushed outside to tell the two women that while they had been talking, Szlamnik had dropped two pills into the new beer Tatiana had left behind on the table.

“He did it again,” she said.

All three women looked through a window and saw Szlamnik trying to wipe up beer that had foamed over the edge of Tatiana’s glass and was fizzing as if there were Alka-Seltzer in it.

In fact, as Dr. Lemos would later testify, the pills were alprazolam, commonly sold as Xanax, a central nervous system depressant prescribed to relieve anxiety. “In combination with alcohol,” Lemos testified at the preliminary hearing, the two drugs “are encountered frequently in drug-facilitated sexual assaults … without giving the victim the chance … to even realize what’s going on.”

On the sidewalk, Tatiana was sobbing. Bridgeman-Oxley stalked back into the bar with Tatiana following, swiped the foaming glass off the table and looked the stunned Szlamnik in the eye when he began to protest that she had served him a second bad beer.

He said to Tatiana, “Let’s go.”

“Your date’s over, mister,” the bartender told him. “She’s staying with us.”

After offering to buy everybody a shot of whiskey, Szlamnik fled while Bridgeman-Oxley was calling the police, who arrived quickly and took possession of the two beers.

And the quick-thinking barmaids of Noe’s — a jukebox joint that Bridgeman-Oxley describes as “pretty chill” — became heroines.

“These were two heroic people who stopped this crime from happening,” said Susan Breall, the judge at the preliminary hearing.

Lynn Parrish, the spokeswoman for the Rape, Abuse and Incest National Network, agreed: “I don’t remember hearing another story like this,” she said. “They’re heroes in my book.”

Last Tuesday, Judge Bouliane sentenced Szlamnik, who had no prior criminal history, to one year in jail but suspended six months of that. Szlamnik entered jail voluntarily in January after agreeing to plead guilty to transporting and furnishing a narcotic rather than to a crime directly related to a planned sexual assault. He is due to be released in May.

At the time of his plea, he was terminated by the school district, said a spokesperson.

Cormican had arrived in San Francisco from Fargo, N.D., only six months prior to the incident and still works at Noe’s. She shrugs off any attempt to call her a heroine.

“It’s just the kind of place where everybody looks out for everybody,” she said recently while working behind the bar. “I mean, people look out for me. I hope.”