Yes.
Solution one: the simplest.
Your wifes first husband is still alive.
He first threatens her and then proceeds to carry out his threats.
If we accept this solution, our problem is to discover how he got in or out without being seen.
Solution two: Mrs Leidner, for reasons of her own (reasons probably more easily understood by a medical man than a layman), writes herself threatening letters.
The gas business is staged by her (remember, it was she who roused you by telling you she smelt gas).
But,if Mrs Leidner wrote herself the letters, she cannot be in danger from the supposed writer.
We must, therefore, look elsewhere for the murderer. We must look, in fact, amongst the members of your staff.
Yes, in answer to a murmur of protest from Dr Leidner, that is the only logical conclusion.
To satisfy a private grudge one of them killed her. That person, I may say, was probably aware of the letters or was at any rate aware that Mrs Leidner feared or was pretending to fear someone.
That fact, in the murderers opinion, rendered the murder quite safe for him.
He felt sure it would be put down to a mysterious outsider the writer of the threatening letters.
A variant of this solution is that the murderer actually wrote the letters himself, being aware of Mrs Leidners past history.
But in that case it is not quite clearwhy the criminal should have copied Mrs Leidners own handwriting since, as far as we can see, it would be more to his or her advantage that they should appear to be written by an outsider.
The third solution is the most interesting to my mind.
I suggest that the letters are genuine.
They are written by Mrs Leidners first husband (or his younger brother), who is actually one of the expedition staff.
Chapter 16.
The Suspects
Dr Leidner sprang to his feet.
Impossible!
Absolutely impossible!
The idea is absurd!
Mr Poirot looked at him quite calmly but said nothing.
You mean to suggest that my wifes former husband is one of the expedition and that she didnt recognize him?
Exactly.
Reflect a little on the facts.
Some fifteen years ago your wife lived with this man for a few months.
Would she know him if she came across him after that lapse of time?
I think not.
His face will have changed, his build will have changed his voice may not have changed so much, but that is a detail he can attend to himself.
And remember,she is not looking for him amongst her own household.
She visualizes him as somewhere outside a stranger.
No, I do not think she would recognize him.
And there is a second possibility.
The young brother the child of those days who was so passionately devoted to his elder brother.
He is now a man.
Will she recognize a child of ten or twelve years old in a man nearing thirty?
Yes, there is young William Bosner to be reckoned with.
Remember, his brother in his eyes may not loom as a traitor but as a patriot, a martyr for his own country Germany.
In his eyes Mrs Leidner is the traitor the monster who sent his beloved brother to death!
A susceptible child is capable of great hero worship, and a young mind can easily be obsessed by an idea which persists into adult life.
Quite true, said Dr Reilly.
The popular view that a child forgets easily is not an accurate one.
Many people go right through life in the grip of an idea which has been impressed on them in very tender years.
Bien.
You have these two possibilities.
Frederick Bosner, a man by now of fifty odd, and William Bosner, whose age would be something short of thirty.
Let us examine the members of your staff from these two points of view.