But she won't stop calling, and she won't stop writing to anyone who will listen.
"As I'm getting older, I think, 'Did I do enough?' " she said. "It's very difficult to face my life getting shorter. How much more time do I have and who else will take up the cry when I'm gone?"
Rostron was found beaten and stabbed more than 30 times in her apartment at the now-demolished Passyunk Homes. Her pants were missing, her car was stolen and her killer was never found.
When Hummel read a recent article on Upper Darby Police Superintendent Michael Chitwood - a former Philadelphia homicide detective who was the assigned investigator on her mother's case - she was moved to write him last week.
"And so I wait," she wrote. "I'm 80 years this April - and I cry every day."
Chitwood, a lawman known more for his brazen language than his soft touch, was moved by Hummel's words.
"If somebody takes the time to write me a letter like that, then I'm going to take the time to meet with them," he said.
Chitwood drove to Hummel's Willow Grove home yesterday. He couldn't promise her much, but it was more than she'd had in 34 years.
"I was absolutely stunned that he called," Hummel said. "To take the time out was absolutely above and beyond."
Chitwood reached out to a reporter and to Philadelphia Police Commissioner Charles Ramsey, whom he said "couldn't have been any nicer." Chitwood said Ramsey told him he'd have someone on the cold-case squad call Hummel.
Chitwood also promised Hummel he'd use his social-media accounts and the popular social-media accounts of his department to put out the word.
"I remember working on the case," he said. "We did give it our best, but like anything, more comes in and you go to the next one and then the next one."
Rostron, a retired bank employee and widowed mother of three, had lived in the Passyunk projects for 10 years. She drove neighbors to do their shopping and was known as the "cat lady" and loved feeding stray cats, birds and even squirrels, according to a 1980 Daily News article on her death.
In the last five years of her life, Rostron's apartment was broken into four times, but she refused to move because she was worried about what would happen to the animals if she did.
Hummel believes her mother was on the way out of her apartment to do her laundry that Saturday morning when neighbors in the apartment complex who may have been high on drugs forced their way into her mom's home.
"She resisted and that was the end of that," Hummel said.
Back then, DNA technology was not available, and obtaining fingerprints from a scene was very rare, Chitwood said. Hummel's theory could not be proven.
Twenty days after her mom's death, mobster Angelo Bruno was shot to death in his car in South Philadelphia. Hummel fears that case may have overshadowed her mother's.
For the first few years, Hummel held on to hope that her mother's killers would be found. But as the years passed, more and more people told her, "Don't worry about it, they probably got into some problems and they're all dead," she said.
But Hummel, a mother of six, did worry. She still does. She's taken to reading mystery novels and watching A&E's "Cold Case Files."
Chitwood said he hopes that putting Hummel's story back out to the public will draw someone forward who may have been too scared to speak before.
"Maybe 34 years later, people will be more cooperative," he said. "The sad thing is, how many more people are out there asking these same questions?"
Hummel said even if the killer or killers are dead, she would like to know who they are and why they did this to her mother.
"I want to know that it wasn't a phantom who did it but a human being. And why? And for what?" she said. "She probably would have given them anything if they would have knocked on the door, but obviously they wanted more."
Anyone with information on the slaying of Mabel Rostron is urged to call the Philadelphia Police Department's tip line at 215-686-8477.
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