<p>Meriwether Lewis.</p>

People who live in the Columbia-Pacific region are undoubtedly familiar with the fascination surrounding the Lewis and Clark expedition. With a national park spanning sites in both Oregon and Washington, annual re-enactments and the Corps of Discoverys winter fort replica nearby, its easy to feel the mark left by the expedition.

But unless you have read the Lewis and Clark journals (or are fresh from learning about the expedition in school), chances are that some details are murky.

For example, I didnt know that just three years after the Corps of Discovery returned home, Meriwether Lewis died or that the details surrounding his death have inspired such debate among scholars.

To say its a controversy would be an understatement, said David Peck, who is a retired physician and the author of Or Perish in the Attempt: The Hardship and Medicine of the Lewis and Clark Expedition. Peck gave a presentation about Lewis death last Sunday for In Their Footsteps, a free speaker series held once a month in the Fort Clatsop Visitor Centers Netul River Room.

What we know: Lewis died Oct. 11, 1809 from gunshot wounds to the head and chest while on his way to Washington D.C. to settle some financial details with the government about the expedition.

There are four main theories about Lewis death: 1) that Lewis was murdered, perhaps as part of a political conspiracy, 2) that he shot himself while suffering neurological effects of syphilis or mercury (which was used at the time to treat syphilis), 3) that Lewis shot himself to relieve pain from chronic malaria, or 4) that Lewis committed suicide.

Peck discussed the theories, giving his opinion on the evidence and possibility of each.

All were fascinating to hear. Some theories rested on little evidence, which Peck was quick to point out. One thing was clear: its difficult to prove something that happened so long ago. Details are murky, testimony from witnesses is complicated, and medical knowledge at the time was very different from today (germ theory wasnt even a thing yet).

Ultimately, Peck settled on suicide as the most likely explanation for Lewis death.

According to Peck, some people have a difficult time thinking about Lewis being suicidal. To modern eyes, Lewis was a hero and accomplished great things. What did he have to be depressed about? people might wonder.

Lewis may have felt like a failure: The primary objective of the expedition was to find a practical land route across the continent, but they didnt find the Northwest Passage. Peck said that after the expedition, Lewis was relegated to a desk job, though he was poorly suited for political work. Lewis was also unmarried and could have been abusing both alcohol and opium. There is also a suggestion that he may have had Bipolar II disorder, where depression is more prominent than mania.

I dont think this detracts anything from him or what he accomplished, Peck said.

To me, the discussion of Lewis death and the mystery behind it added a tragic twist to my understanding of Lewis and Clark, making their story all the more human and more fascinating.