The family of Meriwether Lewis, co-leader of the Lewis and Clark expedition, announced this morning that they are once again seeking permission to exhume his bones from federal land and determine whether he committed suicide or was murdered.

"What we want is the truth," Howell Lewis Bowen, 73, Lewis's great-great-great-great nephew told the Tennessean. "We've had one roadblock after another. It's very frustrating—every time we take a step forward, we have to take two steps back."

Lewis died in October 1809 just three years after blazing a trail to the Pacific Ocean, rigorously documenting his observations of people, plants, animals and rock formations along the way. The 35-year-old had been governor of the Louisiana Territory and stopped at an inn outside of Nashville, Tenn., on his way to meet President Thomas Jefferson. Two shots rang out that night, and although no one observed his death, a companion later declared it suicide.

Indeed, Lewis was a melancholy character in financial straits and had been struggling to pen a book based on his expedition. Some have speculated he had manic depression or was suffering from syphilis, which in late stages can lead to mental illness. In the book Undaunted Courage, historian Stephen Ambrose claims that Lewis had attempted suicide many times.

But others believe that Lewis was either robbed and murdered or was killed by political enemies. "There were many people in Saint Louis who were unhappy with his decisions concerning property and mining rights and money," historian John Guice told Southern California Public Radio.

To solve the 200-year-old mystery, the family wants to have Hugh Berryman, a forensic scientist at Middle Tennessee State University, examine Lewis’s remains. But because the body is buried on the Natchez Trace Parkway, a trail on federal land, they need approval from the National Park Service, which has refused for the last 10 years. Some have suggested the agency fears it could lead to further exhumations of public figures at national monuments.

Now, the family has engaged on a public relations blitz, enlisting the support of 200 family members, putting together a Web site and hiring a publicist who organized today’s press conference in Washington, D.C.

“The human skeleton is extremely good at telling its own history. It’s almost like you could sit down with Meriwether Lewis and ask him what happened the morning of October 11, 1809,” Berryman said in a statement. “However, we won’t be able to conduct that forensics interview unless we exhume his body.”

Portrait of Meriwether Lewis courtesy Wikipedia