She did indeed know.

Madame Simonneau was born in a social circle which is obsequious to the constituted authorities and respects the dead.

But when, having questioned Monsieur de Ligny, she learnt that he had dragged the body into the front room, she could not conceal from him that such behaviour was imprudent and might expose him to unpleasantness.
"You ought not to have done it," she told him.

"When anyone has killed himself, you must never touch him before the police come." Ligny thereupon went off to notify the commissary.

The first excitement having passed off, he no longer felt any surprise, doubtless because events which, considered from a distance, would seem strange, when they take place before us appear quite natural, as indeed they are.