John Swinnerton was a real-life Salem doctor in the late 17th century. His presence in the novel is another instance of Hawthorne's fondness for mixing real people into fictional situations. (For other examples, see "In a Nutshell.") In the first chapter, John Swinnerton pronounces Colonel Pyncheon dead of natural causes. But we are suspicious of this conclusion, what with Matthew Maule's curse and the gossip that Colonel Pyncheon's body was found with fingerprints on his neck. But John Swinnerton turns out to be telling the truth: Colonel Pyncheon died of the weird Pyncheon-style stroke his family sometimes gets. After the Maule disaster, it seems unlikely that Colonel Pyncheon died a natural death, but there you go – Hawthorne keeps you guessing.