Captain Jonathan W. Archer, fugitive from France

My great great grandfather was said to have fought a duel in or near Paris, France about 1848, and possibly belonged to a family that was nobility before the French Revolution. He was sure he killed a cousin in this duel, and he was maybe 16, so he left France for America, possibly entering near Plattsburgh, NY. He changed his name, so we have no idea who he was, as he refused to even hint at his former identity. He married at age 20 in Shaftsbury, VT, and became a sailor, first on the Atlantic, then sailed the Great Lakes from about 1861 to 1900. I have wanted to find who he was before he left France for over 50 years, but he did a great job of covering his tracks. Is it possible to ever track his family in France?