He would take the facts the prosecution considered most damning and try to reinterpret them as evidence of heroism.
The German Arrest
Petiot's story was not completely absurd on its face.
That was what made it dangerous.
German authorities had actually arrested him during the occupation.
Le Monde's later reconstruction notes that he was arrested by the Germans in May 1943, tortured, and held at Fresnes prison for months before being released. German services apparently suspected that he really was involved in moving Jews or other fugitives out of France.
For Petiot, this was powerful material.
Why would the Germans imprison and torture a man working for them?
Was that not proof he was Resistance?
Not necessarily.
The wartime intelligence environment was chaotic.
German agencies did not always know what other German or collaborationist agencies were doing.
A criminal could be suspected by one service while dealing with people connected to another.
An underground escape operation could be genuine, fraudulent, or both at different times.
Petiot's network had apparently become convincing enough that German authorities investigated it.
That does not mean the supposed passage route actually delivered its clients to freedom.
In fact, the evidence at rue Le Sueur suggested precisely the opposite.
Still, the German arrest gave Petiot something invaluable.
A historical fact he could build a heroic story around.
He had been tortured by the occupiers.
Therefore, he implied, he must have been their enemy.
The prosecution would have to show that suffering at German hands did not erase murder.
A Perfect Defense for 1946
Petiot's trial began on March 18, 1946.
The date matters.
France had been liberated less than two years earlier.
The country was still dealing with the political and psychological aftermath of occupation.
Who had resisted?
Who had collaborated?
Who had done both at different moments?
Who was lying?
Who had profited?
Who had denounced neighbors?
Who had switched sides when liberation approached?
These were not abstract historical questions.
They were living arguments.
So when Petiot claimed he had killed collaborators and Germans in the service of France, he chose the most emotionally charged possible defense.
He was not saying:
I did not kill anyone.
He was saying:
You have misunderstood the killings.
He reportedly claimed responsibility for far more deaths than those charged, boasting that he had eliminated dozens of enemies through a Resistance organization he called "Flytox" or "001." Contemporary and later coverage recorded his claim that those he killed were Germans or collaborators and therefore enemies of France.
It was a remarkable inversion.
The prosecution said:
You preyed on desperate people for money.
Petiot said:
I executed traitors.
The prosecution said:
The escape route was a fraud.
Petiot said:
The secrecy proves it was Resistance work.
The prosecution said:
The valuables prove robbery.
Petiot could argue that wartime operations required money or that the property belonged to enemies.
The prosecution said:
Your house was designed for killing.
Petiot said:
War required killing.
He attempted to turn every horror into patriotism.
The Courtroom Spectacle
The trial became enormous.
Le Monde's report from the first hearing described packed public galleries, overflowing press sections, foreign journalists and photographers. The Petiot proceeding had already become a cultural event before the first arguments were finished.
That spectacle created risks for both sides.
The prosecution could benefit from public disgust.
But the defense could argue that no defendant could receive a fair hearing after years of sensational headlines.
Petiot seemed to understand the theatrical possibilities better than almost anyone.
He joked.
He interrupted.
He corrected details.
He smiled.
He behaved at times less like a frightened defendant than someone attending a performance in which he was the star.
One contemporary Le Monde account described him appearing almost untouched by the accusations, even smiling toward a photographer while the charges were read.
That attitude fascinated the public.
But courtroom personality is not evidence.
The central question remained:
Could his Resistance story survive the actual identities of the dead?
The Victims Fight Back Through Records
The dead could no longer testify.
Their documents could.
Letters.
Suitcases.
Clothing.
Jewelry.
Family testimony.
Last-known movements.
Appointments.
Introductions.
Witnesses who had connected victims to Petiot's supposed escape network.
The prosecution began reconstructing people whom the killer had tried to reduce to categories.
Not "collaborator."
Not "German."
Not "enemy."
A husband.
A wife.
A doctor.
A Jewish family.
A woman preparing to leave.
A man instructed to take valuables.
A person last seen following Petiot toward an alleged route to safety.
Each identity weakened his general claim.
The more individually the victims could be understood, the less convincing it became to declare all of them enemies of France.
The Ministry of Justice later emphasized that his victims were primarily Jews and others trying to disappear, not the universal collection of Nazi agents Petiot claimed.
One of the prosecution's most powerful tools was therefore not medical evidence or architecture.
It was biography.
Give the dead back their stories.
Then ask the defendant why those stories do not match his.
The Intermediaries
The network also depended on people who were not necessarily aware of the killings.
Witnesses described acquaintances referring potential escapees to Petiot.
That made the system scalable.
Petiot did not need to find every victim himself.
His reputation could travel.
Someone knew a man who knew a doctor.
Someone had heard of a safe route.
A hairdresser, acquaintance, patient or intermediary could mention the possibility to someone desperate.
Soon the candidate was meeting Petiot.
During the 1946 trial, witnesses were questioned about how potential travelers were introduced, where meetings occurred, and what instructions they received.
Le Monde's contemporary reporting described one witness acknowledging that people seeking passage were directed to Petiot and told to bring jewelry and limited luggage.
This created another investigative difficulty.
How much did intermediaries know?
Were they innocent?
Naive?
Paid?
Criminal?
Were some connected to collaborationist circles?
Did any suspect what happened after the travelers vanished?
The war had produced networks in which legitimate and illegitimate activity overlapped.
That made clean answers difficult.
Even decades later, historians have continued debating some of the relationships around Petiot, including links between certain intermediaries and collaborationist criminal groups.
The uncertainty does not erase the murders.
It helps explain how Petiot could operate.
A Victim Walks In Carrying the Evidence of His Own Robbery
Imagine the experience from the victim's perspective.
You have decided to flee France.
You cannot use ordinary travel.
Your identity may be dangerous.
Your bank account may become inaccessible.
You gather cash.
Jewelry.
Documents.
Perhaps a few clothes.
You do not tell many people where you are going because secrecy could mean survival.
Someone gives you an address or meeting point.
A doctor explains that the route is organized.
Maybe you will travel south.
Maybe through another country.