Mary Jane Fonder, 75, who committed one of the most notorious murders in Bucks County history and was suspected in the 1993 disappearance of her elderly father, died Monday at the State Correctional Institution at Muncy.

Corrections officials said that Fonder died of cardiac arrest in the prison infirmary.

Fonder had been incarcerated at Muncy since December 2008, when Bucks County Common Pleas Court Judge Rea B. Boylan sentenced her to life in prison for the murder of receptionist Rhonda Smith, 42, in the office of a Springfield Township church.

The murder, which went unsolved for more than two months, riveted the media’s attention for the better part of a year, resulting in at least one television network  documentary and a true-crime book.

But Rhonda Smith’s was not the only death for which Fonder was suspected.

In recent weeks, her name reappeared in headlines as detectives renewed a search in Nockamixon Township for her long-missing father. That search will continue despite her death, District Attorney Matthew D. Weintraub said today.

Edward Fonder III was 83 when he vanished in July 1993 from the house on Winding Road that he shared with his only daughter. He has never been found, and Mary Jane Fonder remained, at the time of her death, the only suspect in his presumed demise, Weintraub said.

Complicating the investigation was Fonder’s refusal to allow police to search the property. After her murder conviction, a surviving brother took the same stance for the ensuing decade.

The property recently was sold, however, to a neighbor who permitted investigators full access to the now-demolished house and the surrounding land.

Detectives have combed the grounds with metal detectors and ground-penetrating radar, but the mystery of Edward Fonder endures.

“The search will continue because the District Attorney’s Office is still concerned about returning the remains to the family for closure and a proper burial,” Weintraub said.

Fonder was the oldest woman ever convicted of murder in Bucks County. A chatty, eccentric woman given to outlandish wigs and petty jealousies, she was once described in court by her own attorney as “the aunt you don’t want to sit next to at Thanksgiving.”

A decade ago, Fonder became infatuated with her pastor at Trinity Evangelical Lutheran Church. When the clergyman showed no interest in her, Fonder perceived Rhonda Smith as a rival for his affections, and fatally shot Smith as she sat at her desk in the church office on Jan. 23, 2008.

Fonder then drove off to a hair appointment, later tossing the murder weapon off an overpass into Lake Nockamixon.

A jury convicted her of first-degree murder on Oct. 30, 2008, but Fonder remained defiant at her sentencing.

“I’m sorry, so very sorry this poor woman was murdered,” she said. “But in the name of God … I did not kill Rhonda Smith.”

Within a year, however, Fonder had accepted responsibility for Smith’s murder. In prison interviews, she told reporters that she didn’t remember shooting Smith, but acknowledged that she had to have been the killer.

Contact: Matthew D. Weintraub, 215.348.6344, mdweintraub@buckscounty.org