The age of swinging singles was humming merrily along whenRoseann Quinn left a bar with a stranger on New Year's Eve, 1972.

It was the last time she was seen alive.

"Young Teacher Slain in West Side Flat," was the Daily News headline announcing her fate on Jan. 5, 1973.

After the Christmas recess, Quinn, 28, had failed to show up for her job at the St. Joseph's School for Deaf Children in theBronx. A worried colleague traveled to the gloomy seventh floor studio on W. 72nd St. that Quinn shared with a cat.

When there was no answer, the super unlocked Quinn's door and found the slender 5-foot-5 redhead sprawled on her convertible bed, naked and covered in blood. A 65-pound statue of a woman, in Quinn's likeness, was lying across her face, which had been beaten. Blood was splattered on the walls.

The medical examiner found 18 stab wounds in her stomach, neck, head, chest and throat. Signs of sexual activity were first labeled rape. Later, though, the coroner said there was no indication that Quinn had resisted. It was likely that the encounter had been consensual and that the killer was someone she knew.

The news was beyond belief. Quinn was a nice girl, with no known enemies. Her childhood in a New Jersey suburb had been ordinary. She was an average student at Morris Catholic High School and graduated from Newark State College, where she studied education.

A spokesman for St. Joseph's, where she had worked since 1969, told the News, "She was a friendly, pleasing personality, not only with the children, but also with the other teachers."

Quinn, who walked with a slight limp caused by polio, taught a class of eight deaf 8-year-olds. By all accounts she was devoted to them, often bringing them breakfast because they had to take long bus rides to school.

Her neighbors liked her too. "We get some weird people around here," said the owner of the local dry cleaner. "But this girl was different. She was very nice and quiet and shy. She wore skirts and blouses, not this hippy stuff."

In one way, though, this old-fashioned girl was a creature of the swinging '70s. She was among the newly liberated who were rejecting marriage and trying to make their own money and live on their own terms.

Like many of these bachelorettes, Quinn spent much of her free time in bars, sipping wine, reading books and looking for love. She had no regular boyfriend, but an acquaintance said she was "the type of girl who would have a guy in if he brought her home."

On New Year's Eve, Quinn and two male companions had been spotted at a few neighborhood watering holes, welcoming in 1973 at W.M. Tweeds, a W. 72nd St. bar named for the corrupt 19th century politician Boss Tweed. One of her companions went home early and alone. The second left with Quinn, heading to her apartment across the street.

Dozens of detectives got on the case, scrutinizing Quinn's every move that night, talking to anyone who knew her and strangers who might have seen her. From interviews, a police sketch artist recreated the face of the "bar beau," the man who had followed her out of Tweeds.

Four days after Quinn's corpse was discovered, police tracked her escort down halfway across the country, at his brother's apartment in Indianapolis. He wasJohn Wilson, a 23-year-old drifter with a wispy blond moustache and a long rap sheet. He had been roaming the country since he dropped out of high school after two years, and had been arrested at least five times - in Florida andKansas City.

At the time of Quinn's slaying, Wilson was a fugitive, having busted out of aMiami prison on July 6.

Wilson was hardly a suitable marriage prospect for a girl of Quinn's caliber, but good enough for a one-night stand, which was part of the culture in the Swinging '70s. Newspapers ran features like, "A Girl's Guide to Guy Chasing," and advised young women to "Mingle, but Stay Single."

It seemed like hip, sexy fun, until the Quinn case gave a stark reminder of the dangers of letting strangers into your bedroom. A day after her body was found, a Daily News feature carried the headline, "Once more, bachelor girls ask: Who's Next?"

One of these singles was Judith Rossner, new to the city after the dissolution of her 17-year marriage. Rossner, a novelist, found the singles scene desperate and lonely, and saw in Quinn a perfect symbol of the downside of swinging. Her novel, "Looking for Mr. Goodbar," sailed onto the bestseller lists in 1975. Two years later it was made into a grim, bloody movie, starring Diane Keaton and Richard Gere.

But neither Quinn's murder, nor the terrifying depiction of it on page and screen, discouraged the die-hard swingers. They cruised along for about a decade, until an invisible killer - the AIDS virus - drained the last bit of fun out of all the bar- and bed-hopping.

Wilson would not live to see his fictional counterpart. On May 5, 1973, while awaiting trial in the Tombs, he fashioned a noose out of a bed sheet and hanged himself from a ceiling fixture in his cell.