(I believe you would make a far better reporter than a mathematician, but that's beside the point.)

For the moment, we should search this cabin further in the hope that we may find evidence of Mr. Erickson's involvement, either directly or through an accomplice. Certainly he has the motive; we're only legally allowed to search here at all because of that very motive combined with the decisive lack of one on the part of Mr. Condon.

Thus far, we've discovered something highly likely to have provided Mr. Erickson with half of the means as well. However, we need decisive proof that he either met with Mr. Condon or arranged for someone else to do so, and that either he or whatever accomplice he may have has access to the poison.