The Voting Dead Project by Bill Smith

On sabbatical in the Pacific Northwest, Caden Cole learns of his best friend's murder and becomes fixated on finding Ben Dunn's killers. Using his dead friend's journal entries on his thumb drive, Caden discovers Ben worked on a secretive project that plans to use grave sites as voting booths to shape future presidential elections. The story takes place primarily in two Southern cemeteries where a medium interviews dead Confederate soldiers and their sons as future voters. Caden soon realizes his investigation is putting him and his new friends in grave danger.