Why Wouldn't People Think of a Serial Killer?

Could it have been just a random mass murderer or cerial killer? And why wouldn't people at the time think of that possibility? I can't say nobody thought of it, but i haven't found it in the reading i've done on the case. It's hypothetically possible that someone just wanted to kill all these people, either for no motive or for no political motive. But people were certainly justified at the time in seeing a political motive between the two waves of sickness that seemed to focus on president buchanan and his associates. On the other hand, as we'll see in a bit, that connection isn't as clear as it seemed at the time,. Four groups were accused