Mary Elizabeth ate several pieces.
Her older sister, Ida Harriet Deane, also ate some.
Others sampled the chocolates as well.
Children and visitors were exposed.
Later accounts identify several people who became ill but survived, including young members of the family and at least one visiting girl who would later travel to California to testify.
The poison had been concealed inside something meant to be shared.
The sender could not completely control who ate it.
That night, the consequences began.
Everyone Who Ate the Candy Became Sick
The symptoms appeared within hours.
Nausea.
Severe stomach pain.
Vomiting.
Weakness.
The household that had spent the evening sharing candy was suddenly dealing with multiple sick people at once.
At first, poisoning was not automatically obvious.
Foodborne illness was common in the nineteenth century.
Refrigeration was limited.
Doctors frequently saw violent gastrointestinal diseases.
The family had eaten an evening meal before the chocolates.
There were several possible explanations.
Perhaps something served at dinner had spoiled.
Perhaps an infection was moving through the household.
Some early medical discussion reportedly considered gastrointestinal illness rather than deliberate poisoning.
But there was a problem.
The pattern followed the candy.
People who had eaten it became sick.
Those who had consumed more were in greater danger.
And the two adult sisters deteriorated terribly.
Ida Deane died first.
Mary Elizabeth Dunning died soon afterward.
Accounts generally place Ida's death on August 11 and Mary Elizabeth's on August 12.
Within roughly two days of opening the package, John and Rebecca Penington had lost both daughters.
Other people survived.
That difference would later become medically significant.
The two women who had eaten more candy had received a much larger dose.
What had looked like confectionery had behaved like poison.
The Double Funeral
Dover was shaken.
The Peningtons were not anonymous residents.
John B. Penington was known throughout Delaware.
Now two of his daughters had died almost simultaneously after an inexplicable illness.
Their deaths drew enormous attention.
They were buried together.
Historical accounts describe a huge turnout for the funeral, with the community mourning two women whose lives had ended within hours of each other.
But grief was already turning into suspicion.
The father did not accept that this was an ordinary illness.
Something about the candy bothered him.
Two daughters.
Same symptoms.
Same night.
Same mysterious package.
And other people who had eaten the chocolates had become sick.
The box that initially looked like a gift began to look like the common denominator.
Some of the candy remained.
That was crucial.
If every piece had been eaten, investigators would have lost their best physical evidence.
Instead, samples could be examined.
And when chemists tested the remaining sweets, the case changed completely.
Arsenic.
Poison Inside Chocolate
Arsenic had a long and notorious history as a poison.
By the nineteenth century it was hardly unknown to doctors or detectives.
It could be obtained for legitimate purposes.
It was used in industry and household products.
But when introduced into food in sufficient quantity, it could cause violent gastrointestinal illness and death.
Chemical testing of the surviving candy detected arsenic.
Accounts of the case described the poison as having been inserted or incorporated into individual pieces rather than merely contaminating the box accidentally.
This was no manufacturing accident.
Someone had deliberately turned chocolates into a delivery system.
That discovery produced a new question.
Who had prepared them?
The package had come through the mail.
No one in Dover had seen the sender.
The victims had no confrontation with an attacker.
The person responsible might never have been east of the Mississippi.
The physical crime scene and the perpetrator could be separated by a continent.
In 1898, that was an extraordinary investigative problem.
A Murder Without a Local Murderer
Most homicide investigations begin close to the victim.
Family.
Neighbors.
Business associates.
Someone seen near the house.
Someone with a weapon.
Someone whose footprints remain at the scene.
This case had no such obvious local trail.
The box itself was the visitor.
Whoever had created it had delegated the final step to the victim.
The murderer did not have to watch Mary Elizabeth eat the candy.
The murderer did not have to know exactly when she opened the parcel.
The murderer did not have to enter the house.
Everything depended on one assumption:
She would trust the gift enough to eat it.
That is what made poisoning by mail such a frightening concept.
Distance became part of the weapon.
The postal service carried the poison.
The victim opened it.
The victim completed the mechanism.
Police now had to reverse that movement.
Start in Dover.
Follow the package backward.
Find California.
Then find the hand that had placed it into the mail.
The Note
Before investigators had a suspect, they had handwriting.
"With love to yourself and baby."
"Mrs. C."
It was very little material.
But John B. Penington remembered something.
The anonymous letters.
Those earlier messages about his son-in-law's affair had also come from California.
He had kept them.
Now he could place the letters and the candy note together.
Same family.
Same target.
Same distant city.
And to his eye, something about the writing appeared similar.
That did not prove one author.
Handwriting comparison in 1898 was not the exact science modern viewers may imagine from forensic television.
But it was already an established investigative practice.
People developed distinctive habits.
Letter forms.
Spacing.
Slant.
Connections between characters.
Capitalization.
Pressure.
Ways of forming particular words.
The anonymous letters became evidence because someone had chosen to torment Mary Elizabeth before choosing to send candy.
If the same person wrote both sets of messages, the investigation could move backward through motive.
Who in San Francisco cared whether Mary Elizabeth reconciled with John Dunning?
There was an obvious person to ask.
John Dunning himself.
A Telegram Across the War
Dunning was away covering the aftermath of the Spanish-American War.
News reached him that his wife and sister-in-law were dead.
He headed home.
The reporter who had spent years asking other people questions was about to become the most important witness in a sensational murder investigation.
By the time he returned, the basic facts were already terrifying.
Mysterious candy from San Francisco.
Arsenic.
Anonymous notes.
Two dead sisters.
Penington showed his son-in-law the handwriting.
Dunning recognized it.
According to several accounts, his reaction was immediate.
Cordelia.
Whether the moment occurred exactly as later retellings dramatized it, the substance is well documented: Dunning identified Botkin as a likely source of the writing and gave investigators a motive connecting San Francisco to Dover.
Suddenly, a murder that had seemed geographically impossible acquired a human connection.
Mary Elizabeth's husband had a lover in San Francisco.
The lover knew he intended to return to his wife.