I recently made the acquaintance of Lynne Garvey-Hodge, a Fairfax County History Commissioner, who also knew of it. She was kind enough to send me a copy. I link to a .pdf copy here for your reading pleasure.
Summary: On October 27th, 1855, Lewis Q. Hall of the local Hall family was attacked by William H. Keene (owner of the Old Keene Mill which the street in Springfield and Burke is named after). Keene used a knife; alcohol was involved. Hall died, and Keene was tried and condemned to hang on 30 January 1857. Virginia's Governor Wise changed the punishment to ten years in prison in Richmond. We lose track of William H. Keene due to records being destroyed as a result of the Civil War.
The article is fascinating, and gives an interesting account of some local 19th C. history most residents are unaware of these days.
Whenever I drive by the site of the Old Keene Mill - at the intersection of Old Keene Mill Road and the Pohick Creek, I think about the events that took place there in 1855!
LINK: An interesting "suburban archaeology" article about the Keene Mill is here.
Allie Guidry has found some interesting mentions of the case from the Alexandria Gazette:
From November 24th, 1855.
From April 5th, 1856 - Keene was an escapee!
From November 10th, 1856.
From January 17, 1857.