"No.

The police seem very dense, and this plain fact has not yet occurred to them.

Their theory is the same as what you suggest, but my own is something quite different, Mr.Gregg.

I believe that a second person also fell a victim," she added in a low, distinct tone.
I gazed at her open-mouthed.

Did she, I wondered, know the actual truth?
Was she aware that the woman who had fallen there had disappeared?
"A second person!" I echoed, as though in surprise.