"Malcolm soon received a cryptic response from “Kelly”: a complaint that the abrin “did not work.”
Just what the hell this is supposed to mean cannot be known at this time."
Of course it "can be known" if you think about it, just a tiny bit. It means he tried it out, administering it to someone or something, and that person or creature didn't die. Come to think of it, police should see if they can link him to the cases of poisoned meatballs left around town over the last couple of years. Perhaps he was doing test runs with rat poison, to later ramp up to killing people with what he believed to be "untraceable" poisons. Poisoners are sneaky, devious people. He seems to fit the profile.