Driving to an old friend's home, Betty Tyson shrinks down in her seat when she spies a police car.

"They're waiting for me to slip, and they can wait until hell freezes over," she explains, a steely edge transforming her soft voice.

Freed on the basis of new evidence after nearly a quarter-century in prison, Tyson lives in dread of some minor blunder getting her locked up again. After all she has been through, her 18 months of freedom have not diminished her uneasiness. "I wake up in the middle of the night crying, at any given time," she says.

In February 1974, Tyson got 25 years to life imprisonment for the strangling death of Timothy Haworth, a Philadelphia business consultant who left his Rochester hotel around midnight on May 24, 1973, apparently to look for a prostitute. In May 1998, a judge overturned her murder conviction, ruling that the police had withheld exculpatory evidence.

Tyson went to prison at age 25. She got out a few weeks before her 50th birthday; by then she was the longest-serving female inmate in New York state.

She still feels adrift without prison routine. One of her good friends, oddly enough, is a former jailer, Girlie Goodwin, and Tyson is driving to Goodwin's lakeside cottage to visit.

Surrounded by cactus plants and glass ornaments, the two women sip chamomile tea and reminisce about the old days, before the murder, when Tyson was a teenage prostitute in and out of Monroe County Jail--strung out on heroin and doubled up on the floor for days--and Goodwin was kind to her.

Goodwin thinks those times weren't all bad. "When we were in jail together," she begins, and breaks off, saying: "Oh! That sounds awful!" Tyson laughs hard, exposing a gold front tooth.

When Tyson went to jail for the murder, Goodwin had retired. But they continued to write to each other, and Goodwin sent her jailed friend a pair of shoes.

"Now you have a chance to live your life," the elderly woman says. "God has given you a chance, even if it came 25 years too late."

Tyson was convicted on the basis of a confession she insists was beaten out of her by a rogue detective, and on the testimony of two teenage runaways, one of whom revealed long afterward that the same detective had terrorized him into lying. There was no physical evidence against her.

Tyson, who is black, was convicted by 12 white men. As she was led away, she let out a huge scream. "It was like the unknown had came out of me," she says.

It took six years to push away the rage. Finding solace in the Bible, Tyson became a model inmate in Bedford Hills prison north of New York City. She counseled women with AIDS, earned a printer's apprenticeship and won prizes for photography, accolades for her aerobics classes and adulation among younger inmates who came to know her as "Mom."

"All that bitterness and anger left me in the late '70s," Tyson says, sitting on a deck railing behind her new, three-bedroom Colonial in Greece, a Rochester suburb. "I was able to dig down inside to see who this bad person was. I wasn't a goody two-shoes, but the fact of the matter is I didn't kill anybody."

Her mother, Mattie Lawson-Buchanan, came by bus to visit every month. No one else did. After Tyson's release, she arranged a reunion with a drug-addicted son Buchanan hadn't spoken to in a year. The two women slept in the same bed. They talked for hours around the kitchen table. They had five months together before the mother died of emphysema.

Tyson is determined to have a family of sorts. Two brothers with drug records moved in with her in October. Over the last year, she has helped her baby sister, Altimeese, and her four brothers kick heroin, cocaine and alcohol addictions.

"Betty is a hero in her family," remarked a friend, Marge Booker. "It's as if her mother passed the mantle of matriarchy to her."

Tyson grew up fatherless in a family of eight children, mired in a poor urban neighborhood. She was constantly in trouble for fighting and stealing, dropped out of school at 14 and turned to prostitution to feed a heroin habit.

She says she was asleep at home when Haworth, 52, was battered with a brick and asphyxiated with his necktie in an alley. Police found tire tracks near the body and rounded up prostitutes who had cars. Only after Tyson was charged did they realize that her car's tire treads didn't match.

During her interrogation, Tyson says, she overheard John Duval, a transvestite prostitute, assert that she was with him. A screaming match ensued and detectives handcuffed her to a chair.

"That's when they commenced the beating," she says, her eyes brimming with tears. "They took turns. Here I am, a drug addict, a woman, and these burly men are kicking me in my back."

Tyson says chief detective William Mahoney of the Rochester police eventually forced her to sign a confession she later recanted. Mahoney, investigated repeatedly for allegedly abusing suspects, resigned in 1980 after fabricating evidence in an unrelated case. He died in 1981.

In 1997, Wayne Wright, one of the teenagers who testified against Tyson and Duval, admitted he had lied about seeing them with the victim because Mahoney had threatened to kill him.

Prosecutors then came upon a buried synopsis of a police interview with the other teenager, Jon Jackson, in which he also denied seeing them with the victim. Ruling the evidence had been wrongfully suppressed, a judge freed Tyson. In April, Duval's conviction was reversed for the same reason.

While prosecutors decided not to retry Tyson, they opted to go after Duval again.

Tyson won't be attending his trial in January. She wants nothing to do with him.

A year ago, the city gave her $1.2 million in compensation. She splurged $45,000 on clothes, gifts and vacations, later bought a car and a house, then sank the rest into a retirement account.

She fills her days visiting family and select "drug-free" friends, tells her story to church and school gatherings, seeks out mentally ill inmates to visit, and helps periodically in soup kitchens.

Unable to find work as a printer, she earns $143 a week cleaning a day-care center and talks half-heartedly about becoming a social worker.

Tyson grasps hold of small joys: working out in her basement gym, feeding her year-old nephew, riding her lawn mower around the yard. "I'm doing the things that normal people do," she says, and her mournful brown eyes light up.

But her lost years still haunt her. "If I could stay busier, then I wouldn't think as much about the years I've missed," she says. "I just feel lost."

CAPTION: Betty Tyson visits her mother's grave in Rochester. The two had only five months together after Tyson's release.