Betty Tyson, a woman who spent 25 years in prison for a 1973 murder until being exonerated on the basis of new evidence, has died in upstate New York, her sister said Wednesday.

Tyson, 75, died at a Rochester hospital on Aug. 17 following a heart attack and will be laid to rest Friday, said sister Delorise Thomas. Thomas noted her sister had recently marked a milestone, having spent as much time in freedom after her incarceration as she had behind bars.

“It felt good. She was free,” Thomas, 72, said by phone from her Rochester home, where Tyson also lived. “She enjoyed herself, going out driving, playing cards, going out to different parties ... She enjoyed her life.”

Tyson was sentenced to 25 years to life in prison in February 1974 for the death of Timothy Haworth. The Philadelphia business consultant had left his Rochester hotel around midnight on May 24, 1973, apparently to look for a prostitute, and was found strangled with his necktie in an alley the next day.

In May 1998, a judge overturned Tyson’s murder conviction, ruling that the police had withheld exculpatory evidence.

Tyson had entered prison at age 25 and was just shy of her 50th birthday when she was released, by then the longest-serving female inmate in the state of New York.

While in prison, Tyson let go of her rage and found solace in the Bible, she told The Associated Press in 1999, about 18 months after leaving Bedford Hills Correctional Facility north of New York City. As a model inmate, she counseled women with AIDS, earned a printer’s apprenticeship, led aerobics classes and became known as “Mom” to younger inmates.

“All that bitterness and anger left me in the late ’70s,” Tyson told AP. “I wasn’t a goody two-shoes, but the fact of the matter is, I didn’t kill anybody.”

Tyson had grown up fatherless in a family of eight children, dropped out of school at 14 and turned to prostitution to feed a heroin habit. She and another prostitute, John Duval, were convicted of Haworth’s murder on the basis of confessions they said were beaten out of them by police, and on the testimony of two teenage runaways, one of whom revealed long afterward that the same officer had terrorized him into lying.

Tyson’s conviction was overturned after a previously unknown police report was discovered which documented that the other teenage witness said he had not seen either Tyson or Duval with the victim. Duval’s conviction was overturned in 1999.

Tyson received a $1.25 million settlement from the City of Rochester but would struggle financially after prison. Unable to find work as a printer, when she spoke with AP she was earning $143 a week cleaning a day-care center.

“She was a very kind person. She helped anyone that needed help,” Thomas said Wednesday. “I tried to tell her, ‘You know you can’t help everybody, now.’ She did. She did as much as she could.”

In the months before her heart attack, Tyson had spent time with an ailing older sister, who died in April, Thomas said, and a younger sister who died less than a month ago. She loved her big “crazy family,” Thomas said.

“We all get together and laugh and talk about the old times and eat good food,” Thomas said, “talk about our mother.”

Their mother, Mattie Lawson Buchanan, died of emphysema just five months after Tyson’s release.