Six months after a fiery crash in Woodacre killed four teenagers, Marin County prosecutors have charged the 16-year-old driver with misdemeanor vehicular manslaughter, while families of the victims have filed 10 wrongful death claims alleging that the county’s negligence contributed to the tragedy.

The teenaged driver was heading west from Fairfax toward Woodacre on the evening of April 18 when her S.U.V. veered off the narrow, winding and forested San Geronimo Valley Drive, struck a…