It becomes clear what Mr. Greene was talking about, when he publishes an editorial for the newspaper about the dead bodies not getting "proper medical autops[ies]" (25.2). (Um, and we have to say that he might have a point.) The county police are being called in.
Since she's the current medical examiner, Miss Volker is not happy with this.
She dictates a rebuttal to Mr. Greene, in which she argues that the old ladies have died of natural causes.
Jack's mother begs to differ. She thinks her mushroom casseroles are to blame.
But this theory is quickly discarded, since her family has also been eating the casseroles, and they're very much still in the land of the living.
Jack's dad takes advantage of the situation (neighbor will be pitted against neighbor because of the deaths) to again suggest that the family move.
Jack has another major realization: he still doesn't know why things happen (despite reading tons of history books and knowing tons about historical events).
Logically going through events in his mind, Jack identifies possible suspects for the "murders": Miss Volker, Mr. Huffer, and Mr. Spizz. They all are linked to the poison in some way.
He's worried that he'll be accused, since out of all of the people he identifies, he is the only one without a legitimate reason for buying the poison—and, of course, when he wakes up after this very stressful night, his pillow is soaked in blood.