In my exchanges, I often hear this remark: “There is no evidence.”
There is no evidence of innocence, no evidence of guilt. In short, there is never any evidence…
It is therefore necessary to explain what “evidence” means in the Seznec case. It is a judicial case that has now become a historical case. We must therefore distinguish between evidence from a judicial standpoint and evidence from a historical standpoint. These notions are often confused.
Since 2018, my research has been purely historical. It could potentially be used in a request for retrial, but it inevitably leads to proving one single thing: that there is reasonable doubt as to Guillaume Seznec’s guilt. As Denis Langlois keeps insisting, that doubt should have benefited the accused.
The difference between judicial proof and historical proof can be summarized as follows: the first is used to judge, the second to understand.
1. Judicial proof (in a court of law)
Judicial proof serves to decide whether a person is guilty or innocent.
It has four essential characteristics.
1.1 It is governed by strict rules
A judge cannot accept just anything. For example, a confession obtained under coercion is invalid; illegally obtained evidence may be excluded; certain testimonies are inadmissible.
Legal truth is procedural truth: what matters is what can be lawfully proven before the court.
1.2 It is binary
The court must decide: guilty or not guilty. Even if reality is blurred, the law requires a clear decision.
1.3 It targets a specific individual
One does not judge “history,” but a person, for a specific act, on a specific date.
1.4 It requires a very high level of certainty
In criminal law: beyond reasonable doubt. If too much doubt remains, the accused must be acquitted, even if they may be guilty.
2. Historical proof
Historical proof serves to understand what happened in the past. It operates differently.
2.1 It is not limited by legal rules
The historian may use:
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private letters
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cross-checked rumors
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incomplete archives
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late testimonies
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statistics
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objects, photographs, physical traces
Even a biased source is useful—if its bias is understood.
2.2 It is cumulative and probabilistic
A single source is almost never enough. The historian accumulates clues until one explanation becomes the most probable.
He does not say, “This is proven 100%,” but rather, “This is the strongest explanation based on all available sources.”
2.3 It concerns processes, not only individuals
History seeks to explain:
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systems
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collective decisions
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social dynamics
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deep causes
Not only “who did what,” but why and how.
2.4 It accepts uncertainty
In history, one can perfectly well conclude: “We will probably never know for sure.” And that is not a failure.
3. Proof as a source of conflict
Something may be unproven in court yet almost certain historically.
A typical example: an old crime with no direct witnesses and no legal evidence.
→ the court cannot convict
→ yet the historian may conclude with high probability
That is why saying “he was never convicted” is not the same thing as saying “he is historically innocent.”
4. Proof in the Seznec case
In the Seznec case, there is a judicial truth and a historical truth.
The judicial truth is that Seznec killed Pierre Quémeneur in order to seize his property in Plourivo. He committed forgery in private documents.
This judicial truth rests on no physical evidence: a murder without a body, without a murder weapon, without witnesses. The crime scene is unknown. The credible timeline remains vague. But the matter was judged. The judicial file has been closed since 1924. The justice system has never reopened it, under the principle of res judicata. Attempts at retrial cannot succeed, because once a matter has been judged, it becomes a judicial truth. Doubt has been excluded. One may wonder whether fundamental principles of law were violated. That is a debate among jurists.
In 2026, there will never again be any possible judicial proof of innocence. Denis Le Her Seznec devoted his entire life and energy to it without result. The witnesses are dead; the exhibits, if they ever existed, have disappeared. Unless Quémeneur’s remains were found—which is highly unlikely—nothing would probably change. And even then, how would that prove Seznec’s innocence?
5. Historical research
In 2015, Denis Langlois attempted to provide proof of Guillaume Seznec’s innocence by publishing his book Pour en finir avec l’affaire Seznec. This book is important. The testimony is serious and disturbing, but it does not provide judicial proof of innocence. It does not follow legal formalities. It is late. It is not corroborated by material evidence. It was dismissed by the courts without serious examination. Historically, however, it allows certain leads to be supported or corroborated.
The question today is: can historical research and historical evidence lead to the judicial exoneration of Seznec?
In English or American law, the answer would be yes. In French law, in my opinion, it is impossible.
I became passionate about the Seznec case, probably beyond reason. I conducted research on the Cadillac affair and on the American known as Sherdly. The investigative and police files contain many facts. They are precise, rigorous, and uncontested. I hypothesized that if there had been a Cadillac affair with Soviet Russia, it would inevitably have left traces.
I therefore began an investigation that had never been undertaken by either the police or the justice system at the time. This historical investigation led me to discover the American hidden behind the approximate name “Sherdly.” I used a methodology employed in historical research, proceeding by elimination. Only one name emerged. When realistic administrative constraints are taken into account—passports, visas, passenger lists, residence and professional status—the range of plausible candidates narrows considerably. Under these conditions, only one documented individual is known to satisfy all the criteria simultaneously.”
It is historically proven that there really was a Cadillac affair with Soviet Russia as described in the investigative file. From reading that file, one thing becomes clear: it is highly improbable that Seznec could physically have committed the perfect crime of killing Quémeneur.
Today, I am not able to prove that Seznec did not kill. I can prove that reasonable doubt is sufficient and certain enough to benefit the accused Seznec. One of the great principles of French law is that doubt must benefit the accused. That was not the case in this affair. The justice system refuses a retrial even when it violates its own principles. Does it therefore require new evidence to do so? For this reason, this case will remain, for history, the symbol of a miscarriage of justice. It may be a bitter victory for Denis Le Her Seznec.