Spoiler warning: This article contains major spoilers for Netflix’s Monster: The Lizzie Borden Story.
Netflix’s Monster: The Lizzie Borden Story does not hide its answer to the most famous question surrounding Lizzie Borden.
In the series, Lizzie kills her father Andrew and stepmother Abby, with Bridget “Maggie” Sullivan involved in the crime.
But history never established that as fact.
The real Lizzie Borden was charged with the 1892 murders, went to trial in 1893 — and was acquitted. The murders remain officially unresolved.
So how much of Netflix’s story actually happened?
Quite a lot has been changed.
1. Did Lizzie Borden Really Kill Her Parents?
We simply do not know.
Andrew and Abby Borden were murdered inside their Fall River, Massachusetts home on August 4, 1892. Lizzie was arrested a week later and became the central suspect.
But prosecutors never proved her guilt.
Her trial ended with an acquittal on June 20, 1893, and no one else was convicted of the murders.
Netflix makes a much more definite choice.
In Monster, Lizzie and Maggie carry out the killings, turning one historical theory into the show’s fictionalized version of events. Netflix itself describes Ella Beatty’s character as a “very fictionalized version” built from the historical record.
That distinction matters:
The series shows Lizzie as the killer. History does not prove that she was.
2. Did Maggie Help Lizzie Commit the Murders?
Netflix dramatically expands Bridget Sullivan’s role.
The real Bridget, an Irish immigrant who worked as the Borden family’s live-in maid, was inside the house around the time of the murders.
In the series, however, Maggie becomes far more than a household servant. She develops an intimate relationship with Lizzie and ultimately becomes involved in the murders.
There is no historical proof that Bridget Sullivan helped Lizzie murder Andrew and Abby.
The show even reinterprets Bridget’s window-cleaning activity on the day of the murders as part of the pair’s deception. Netflix acknowledges that this is one of the ways the known historical details are reshaped for the drama.
3. The Bertha Manchester Murder Is One of the Biggest Changes
This may be the most striking alteration in the entire series.
Monster depicts Lizzie killing neighbor Bertha Manchester with a hatchet, effectively presenting the murder as a precursor to the Borden killings.
Bertha Manchester really was murdered.
But Lizzie could not have committed that murder as the show depicts it.
Manchester was killed in May 1893, months after Andrew and Abby were murdered. At that point, Lizzie was already jailed awaiting her trial. Contemporary history therefore provides no basis for placing Lizzie at Manchester’s murder.
The real case also had another identified perpetrator: Jose Correa de Mello, a young Portuguese immigrant who had worked on the Manchester family farm, confessed and was convicted.
So Netflix does not merely adjust a minor detail here.
It moves an unrelated murder backward in the timeline and connects it directly to Lizzie.
4. Nance O’Neil Did Know Lizzie — But Not During the Trial
This is another clever mixture of fact and fiction.
Actress Nance O’Neil really did become friends with Lizzie Borden.
But Netflix changes when that happened.
In Monster, O’Neil helps Lizzie prepare the public performance that will help her survive her murder trial.
Historically, the two women did not become friends until 1904 — more than a decade after Lizzie’s acquittal.
The showrunners have openly explained why they changed the chronology: bringing the actress into the trial gave them a dramatic way to portray Lizzie consciously shaping how the jury saw her.
So Nance O’Neil is real.
The timing is not.
5. What About Lizzie Trying to Poison Her Parents?
This part has a historical foundation — but Netflix turns uncertainty into a much clearer narrative.
Before the murders, Lizzie reportedly attempted to purchase prussic acid, a deadly poison, from a drugstore.
That incident became part of the evidence surrounding her case.
Monster transforms the detail into a failed attempt to kill Andrew and Abby, with spoiled oysters becoming part of Lizzie and Maggie’s plan before they resort to a hatchet.
Again, the series takes a suspicious historical detail and supplies something history cannot:
a definite motive and explanation.
6. Did Lizzie Really Burn a Dress?
Yes — this is based on testimony from the historical case.
Lizzie burned a dress shortly after the murders, explaining that it had been stained with paint.
Prosecutors considered the incident suspicious.
Netflix turns that historical suspicion into something much more definitive because its version has already decided that Lizzie participated in the murders.
In real life, the burned dress was evidence people argued about.
In the show, viewers already know what happened.
That difference is important.
7. Even the Famous “40 Whacks” Story Isn’t True
The rhyme associated with Lizzie Borden helped create the legend:
Lizzie supposedly gave her mother 40 blows and her father 41.
Those numbers are wrong.
Historical accounts put the number at approximately 18 or 19 blows to Abby and 10 or 11 to Andrew. Abby was also Lizzie’s stepmother, not her biological mother.
The rhyme helped transform a complicated unsolved case into a simple cultural story in which Lizzie was unquestionably guilty.
Netflix’s Monster knowingly plays with that same legend.
So Is Monster: The Lizzie Borden Story a True Story?
It is better described as a fictionalized interpretation of a true unsolved murder case.
The victims were real.
Lizzie was really accused.
She really went on trial.
She really was acquitted.
Many smaller details come directly from the historical record.
But Netflix makes choices history never could: it tells viewers who committed the murders, gives Lizzie and Maggie a specific relationship and conspiracy, moves other events around the timeline, and even connects Lizzie to a separate killing.
That is probably the most important thing to remember after watching the series.
Netflix gives the Lizzie Borden mystery an answer. History still doesn’t have one.