Murderous Mary Mamon

There was something clearly wrong with Mary O’Connor Mamon, but no one ever did anything about it. To be fair, for much of her life there wasn’t anything anyone could do. Over the course of her life she was suspected of a sexual assault on a young girl, admitted killing another, and in an intricate, violent plan, tried to take revenge on the people she blamed for her son’s rejected marriage proposal.
She first appeared in court in the late 1930s, when she was accused of killing a 5-year-old girl in a fit of temper.

The Death of Nancy Glenn


The day after Labor Day 1937, the body of 5-year-old Nancy Glenn was found face down in a mud puddle in suburban Philadelphia. Her corpse was covered by a rusty steel drum, obviously placed there by her killer who wanted to hide the body. Nancy was fully dressed and there was no sign of sexual abuse. She was simply dead.
The coroner called to the scene examined the body and ruled the death accidental. However, Nancy’s family, including legendary West Virginia Football Coach Marshall “Little Sleepy” Glenn, M.D. (that’s correct) refused to accept that verdict and appealed to Philadelphia mayor S. Davis Wilson, who recognized that an injustice had been done.
A subsequent autopsy revealed mud and water in the girl’s lungs, as well as some bruising to her head.
Wilson focused press attention on the case, which in turn prompted a 19-year-old college athlete, Mary O’Connor, to confess to the killing.
A gymnast her teammates nicknamed “Tarzan,” Mary had a breakdown shortly after she killed Nancy Glenn and was admitted as an inpatient in a local sanitarium. Prior to entering the hospital, she confessed her act to her closest friend, Marie Phillips, who went to police.
“I sent her to my bedroom and told her to lie down and rest,” Phillips’s statement read. “She showed me the newspapers and said ‘I am responsible for the death of Nancy Glenn.’”
According to Phillips, Mary told her Nancy had followed her while Mary was riding her bicycle, and saw her fall off. The 5-year-old then reportedly teased the 19-year-old, and demanded a ride on her bike.
“She told me she hit her and the girl screamed, cried, and cried, and screamed,” Phillips told police. “She hit her again to quiet her. She put the body in the road and rode home and washed the mud off her shorts and legs. She told me she burned her gloves.
“On the way home, she met Mrs. Glenn, who asked her if she had seen Nancy, and of course she said no.”
Justice for Nancy Glenn seemed doomed from the time the coroner attributed her death to accident. Mary’s uncle, Common Pleas Court Judge Harry S. McDevitt, spoke to the press about his niece’s case, despite the fact that a fellow jurist from the Philadelphia County court would be overseeing the case. McDevitt provided his own analysis of the case, claiming Mary did not commit the crime, despite admitting it to her friend, her father, and the police.
“It’s possible that she did not commit this crime,” he said. “She may have written the confession just to satisfy her great ego.”
According to McDevitt, Mary’s father Robert claimed his daughter was upset about Marie Phillips’s marriage earlier in the summer.
“She did such strange things as write letters to herself and sign other people’s names to them,” McDevitt said. “She also wrote about herself and mailed them to other people, signing some other name than her own. Her father said she often expressed the desire to see a dead person.”
Mary O’Connor went on trial in February 1938. The trial was a short affair and she was the only defense witness.
On the stand a tearful Mary admitted hitting Nancy Glenn “with the back of my hand.”
“She was standing beside me, I just sort of swung around and hit her with the back of my hand,” Mary said. “Nancy just fell. I felt her pulse, and didn’t know what happened. I thought she was dead,” she went on. “I got a piece of tin from somewhere and put it over her. Then I got out away as quick as possible.”
To her attorney Mary denied intending to hurt Nancy or put her head under water.
At closing, District Attorney Charles C. Gordon told the jury of nine men and three women that Mary was at least guilty of voluntary manslaughter.
“She never gave the child a chance to have that spark of life still in her resuscitated,” Gordon said. “She let Nancy lie dead in the mud.”
Under Pennsylvania law, there are three types of criminal homicide: murder, voluntary manslaughter, or involuntary manslaughter. Voluntary manslaughter requires the state to prove beyond a reasonable doubt that she was “acting under a sudden and intense passion resulting from serious provocation by…the individual killed.” She would be guilty of involuntary manslaughter when as a direct result of the doing of an unlawful act in a reckless or grossly negligent manner, or the doing of a lawful act in a reckless or grossly negligent manner, she caused the death of another person.
After deliberating several hours the jury returned a not-guilty verdict. An audible gasp ran through the courtroom at the verdict and Mary wept hysterically.
There was some fallout from the case. Judge McDevitt was harshly criticized for speaking out before the trial, and the prosecution was lambasted both by the press and the Pennsylvania General Assembly (which convened a blue-ribbon panel to look into the matter).
The fates of several other people — two of whom weren’t even born when Mary was acquitted — may have been different if Mary had been convicted in 1938. She wouldn’t have spent much time in prison even if she had been convicted of the most serious charge, but it might have been possible that she wouldn’t have met the man she married in 1943 and with whom she moved to Levittown, Pennsylvania, where her most serious crimes were yet to come.
Of course, Fate is a tricky thing, and perhaps even if Mary had been punished for the death of Nancy Glenn, her other victims would still have encountered her wrath. That is an philosophical argument for others to have.

The Levittown Attacks


Mary O’Connor Mamon appeared to live a dual life in Levittown, Pennsylvania. She had divorced her husband in 1957 and lived with her four sons. She had a degree in chemistry and worked in that field for a Fortune 500 fruit and vegetable processor. There she was known both as “a dependable, conscientious, and capable” employee and a co-worker who “never seemed to be fond of anybody, didn’t seem to talk much to anyone.”
In her neighborhood, the 49-year-old Mary was as well-liked as any other neighbor.
“Mary’s been in my home several times and she’s always been quite pleasant,” one neighbor told the press. “She wrapped her whole life around her kids.”
She was, however, known for her “husky, mannish appearance” and her preference for “men’s clothes” (Bear in mind this was the 1960s where women were expected to dress “appropriately”).
“Some of women where we bowled did mention however that she’d probably look a lot better if she dressed in women’s clothes,” a bowling teammate recalled.
When Mary was arrested for the murder of Nancy Glenn, her uncle told the press that she “did such strange things as write letters to herself and sign other people’s names to them,” Judge Harry S. McDevitt said. “She also wrote about herself and mailed them to other people, signing some other name than her own.”
This odd and destructive behavior apparently continued while Mary lived in Levittown, and might have contributed to her breakdown.
Mary’s oldest son, Robert, was engaged to Mary Ann Martin, but their relationship soured when Mary Ann began receiving obscene phone calls and was dissuaded from marrying Robert by her aunt, Ethel Markham.
“I told Mary Ann I can’t see him, he’s sissified,” Ethel said. “He was a momma’s boy and kept on his mother’s apron strings.”
Meanwhile, neighbors began receiving anonymous letters about Mary that police later theorized were written by Mary herself. The letters referred to Mary’s arrest and trial for Nancy Glenn’s murder and questioned how the “God-fearing people” of the neighborhood could allow such a person to live among them.
Mary would later testify that she was also receiving obscene and threatening phone calls which she blamed on Mary Ann.
Although Robert vented his frustration by harassing Mary Ann, Mary Mamon focused her rage about the canceled wedding on Ethel Markham and began withdrawing from society. She quit her bowling leagues and became increasingly unstable. Eventually, she was forced to take a medical leave of absence from work.
She hatched a bizarre revenge plot against Ethel that came to fruition on March 23, 1967 — four days before Easter Sunday.
Around 8 a.m. that day, Ethel Markham received a telephone call purportedly from a neighbor, Lorraine Mullery, who said she had received a letter “that concerned the both of them.” The caller asked Ethel to come down to see the letter.
Ethel made the trip down Peony Road but when she arrived at the Mullery residence, she found the door open and sounds that she assumed were coming from the television. No one responded to her knocks and she returned home.
“I did hear something on the stairs,” she recalled later.
About 20 minutes later her daughter, Nancy, volunteered to go down and check on the situation. It would be a life-changing event for the Markham family.
Nancy knocked on the door and a person that she subsequently identified as Mary Mamon pulled her into the house, telling her “that’s OK. You’ll do.”
There had already been a bloodbath in the Mullery home. Lorraine Mullery was dead on the floor of her bedroom awash in blood. At first, police who responded assumed she had been shot in the head.
Her 11-year-old developmentally disabled son, Donald, was lying at the foot of the stairs. He had also been brutally attacked, but was still alive.
When Nancy Markham saw the carnage, she began to scream and tried to escape, but the attacker — who at that time Nancy thought was a man — caught her and began pummeling her with a hammer. The attacker struck Nancy about the head 15 times and left her for dead.
Less than a half-hour later, 13-year-old Patty Mullery returned home from an early morning church service with a neighbor, Andrew Mealey. They discovered the bodies and ran across the street for help.
“I heard screams. It was Patty,” Andrew recalled later. “I went inside and found Nancy lying in the hall.”
Mary Mamon police sketchWhen police arrived at 9:03 a.m., they found the family dog, King, hiding beneath the bed in the room where Lorraine died. Questioning neighbors who saw a “strange man” skulking around the Mullery house, police issued an APB for a white male, 30-to-35 years old, wearing a “cloth car coat.”
However, within a day, after interviewing the Markham family at the hospital where Nancy was in post-operative intensive care, authorities began searching for Mary Mamon and keeping her house under surveillance. Around midnight they saw one of Mary’s sons drive a circuitous route — apparently alone — to a highway out of town.
In a near-unconscious state, Nancy identified Mary Mamon as her attacker.
“She did it! Mary did it,” the teen would later tell police.
At first, everyone believed that Mary had simply made a mistake in attacking Lorraine Mullery’s home (the Mullerys lived at 19 Peony Road while the Markhams lived at 9 Peony Road). However, they soon theorized that Mary had planned to lure Ethel down to the Mullery home to kill her, as well.
“The Mullery home was simply selected as a command post to trap Ethel Markham,” said District Attorney Ward F. Clark.
Mary acknowledged this in her testimony.
“They wouldn’t let me in” to the Markham home, she told the court.
Mamon managed to elude capture for more than a week before reappearing at a convent in Mobile, Alabama, where she surrendered to FBI agents.
It would take nearly a year to extradite Mary from Alabama back to Pennsylvania, and in November 1969, more than two years after the murder and attacks, Mary went on trial.
The month-long trial was fairly cut-and-dried. Police presented a strong motive (her hatred of Ethel Markham for breaking up her son’s relationship), and evidence of planning. Lorraine and Daniel Mullery, and Nancy Markham were simply pawns in her plan.
“It was her intention and frame of mind to commit murder…to slay Ethel Markham and she had to kill Mrs. Mullery lest she be an eyewitness,” Clark said.
The hammer was found in a churchyard a day after the attacks and the handle had been shaved to remove blood stains. The wood shavings with the blood were found in the Mamon home.
On the stand, Mary admitted taking the cloth car coat and shredding it into more than 400 pieces.
“Get rid of it,” she told her son, Robert. “All I need is for a neighbor to tell (police) I had the coat and boots.”
The only part of the coat not recovered was the right sleeve, which police suspected was too bloodstained to be cut up.
Strangely, Mary refused to let her 17-year-old son testify in her defense, despite being the only person who could verify her alibi that she was home the entire day.
“I don’t want him arrested for nothing,” she shouted when her attorney called her son. “No, he’s my boy. I’ll get up and lie to that judge if I have to.”
The case went to the jury on two days before Thanksgiving, and the jurors convicted Mary Mamon of first degree murder. They recommended a life sentence. She died in prison from complications related to emphysema in 1983 after being denied parole several times.
Nancy Markham and Donald Mullery received life terms of a different sort. Both suffered some brain damage and permanent physical effects from the attacks. Donald, who was already developmentally disabled, had to be institutionalized.
Thomas Mullery died in 1971. His daughter said he essentially died of a broken heart.

  • Thomas Mamon

    Did you even do any research to write this “article”? From what I have read it is only a compilation of bias newspaper stories and your imagination. The ‘quotes’ were completely
    fabricated and any real investigation would easily show this. You have clearly demonstrated that good copy sells and journalistic integrity is a myth.

    • Rachel Vaughan

      Get a grip! Mamon was a monster. When we were kidz, the joke was, “if ya don’t behave, Mary Mason’s gonna get ya!”

  • George

    I was 14 years old when this horrible crime took place and that brutal act rocked the Levittown community to its core. Cold blooded MURDER and HAMMER BEATINGS are not fabrications. Wake up.

  • Richard johnson

    Exactly as any family member would say about a murdering piece of crap! You sound so stupid with that crap that you can only be her son! Face the fact that she was pure evil and a waste of human life! You should be locked up for your thoughts , before you hurt yourself or someone else!

  • Jules Gallagher

    Well then Thomas why don’t you give us the real story