Before sinking into the overstuffed easy chair in the middle of her St. Petersburg apartment, a widow named Mary Hardy Reeser slipped into a nightgown and popped two sleeping pills. Hot summer air drifted through the open windows.

It was around 9 p.m. on July 1, 1951. Reeser’s only son, Dr. Richard Reeser Jr., had just kissed her goodbye after a visit. She was alone for the night and decided to enjoy a cigarette before bed.

Reeser, 67, would not be seen alive again. When the landlady, Pansy Carpenter, tried to deliver a telegram the next morning, the door to Reeser’s small apartment on 1200 Cherry Street Northeast was warm and the handle too hot to touch. Inside the charred walls, embers still crackled.

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Firefighters burst into a soot and smoke-filled apartment. Reeser was gone, and only a pile of black ashes remained.

Amid the rubble, police found coil springs from the chair and part of Reeser’s backbone. Her left foot sat in the pile, still wearing a black silk slipper. Her skull, reports say, had “shrunken to the size of a cup.”

Interior photograph of scene where Mary Reeser died. Reeser had moved to St. Petersburg from Pennsylvania several years before her death. [ EVANS, JOHNNIE | St. Petersburg Times ]

Firefighters found evidence of extreme heat. Bare candle wicks towered above puddles of melted wax. Smudges of smoke had stained the tops of the walls. Warped electric switches lined the room.

Lower down, the walls were clean and the electric switches looked normal. Reeser’s newspapers sat untouched. The sheets on her bed were still white.

Reeser’s story is perhaps the strangest unsolved mystery in Tampa Bay history. The case has been documented in magazine articles, documentaries and books. But questions remain.

How could a woman go up in flames without the rest of the room burning? What could have killed Mary Reeser?

***

Mary Reeser and her husband, Dr. Richard Reeser Sr., hailed from Columbia, Pa. A few years after her husband died, she moved to St. Petersburg to be near her son and granddaughters.

Reeser loved her family, needlepoint and entertaining. But Florida was too hot for her liking, and she missed her friends back in Pennsylvania.

Her son could tell she was upset about it on the last day he saw her. She had been too worried about taking a trip back home to eat supper.

The pills she took before he left were the only thing in her system.

***

No one quite knew what to make of the case. But there were plenty of ideas.

Maybe the blaze was an accident. Maybe it was a lightning strike. Maybe, one Times reader proposed in 1951, Reeser died from spontaneous human combustion.

This last theory was the one that spread furthest. Soon the “cinder woman mystery” of St. Petersburg made national headlines.

St. Petersburg Police Chief J.R. Reichart received hundreds of theories from amateur detectives. Some claim that they smelled a strange odor outside of Reeser’s home. Theorists blamed everything from the fabric of the chair cushion to napalm, phosphorus and thermite bombs.

“A ball of fire came through the open window and hit her,” read one letter. “I seen it happen.”

There was no clear answer. So, Reichart drafted a letter to the Federal Bureau of Investigation.

"Dear Mr. (J. Edgar) Hoover,” he wrote. “This fire is too puzzling for the small-town force to handle."

Police sent boxes of evidence to the FBI laboratory in D.C., including “portions of the apartment rug, smoke samples, rubble from the walls and floor and segments of the chair.” FBI agents spent three weeks examining Reeser’s mysterious disappearance.

Finally, on August 8, Reichart released a statement to the media, calling it “the most unusual case I’ve seen during my almost 25 years of police work in the City of St. Petersburg.”

FBI agents found no evidence that suggested lightning had struck Reeser or the building. All of the fuses in the apartment were still intact. And investigators hadn’t been able to detect substances that could have started the blaze.

“Common combustible fluids and accelerants such as alcohol, gasoline, etc. would probably be consumed in such a fire and no trace of them detected afterward,” read Reichart’s statement.

As for spontaneous combustion? The investigation ruled that out as well.

It’s possible that Reeser, drowsy from the sleeping pills she took, dozed off in her chair while smoking her evening cigarette. The nightgown she was wearing at the time of her death was made of rayon acetate and could have caught fire from a cigarette ash.

Reeser had weighed about 170 pounds. Human fat could have fed a fire that smoldered throughout the evening, allowing hot air and smoke to rise to the top of the room.

“Mary was a great smoker,” Ernestine Reeser, Mary Reeser’s daughter-in-law, told the St. Petersburg Times in 1991. “The cigarette dropped to her lap. Her fat was the fuel that kept her burning. The floor was cement, and the chair was by itself. There was nothing around her to burn.”

Investigators decided this kind of accidental death was the most plausible theory. But Wilton M. Krogman, an anthropologist from the University of Pennsylvania, disagreed.

Instead of shrinking, Reeser’s skull should have exploded, he said.

Then there was the cremation of the body, which would have required several thousand degrees over the course of several hours.

“I cannot conceive of such complete cremation without more burning in the apartment,” Krogman said, according to the York Daily Record.

It’s now been nearly 70 years since Reeser’s mysterious death. To this day, no one knows for sure what happened. We may never have answers.

After the FBI investigation trailed off, a portion of Reeser’s ashes were buried next to her husband in Pennsylvania. The rest stayed with her offspring in St. Petersburg.

Reeser’s family once told the St. Petersburg Times they used to feel her presence, at least up until they got rid of her old furniture.

“That’s Grandma again," they used to say when a breeze rolled by. "Don’t worry. She’s nice.”

Times senior researcher Caryn Baird contributed to this report. This story was compiled using Times archives.