SAN FRANCISCO (KGO) -- A skateboarder accused of attacking a security guard in San Francisco will walk a free man.A judge Tuesday said the jury deadlocked and declared a mistrial in the case of 24-year-old Jesse Vieira.Prosecutors say Vieira beat Dan Jansen when he tried to prevent Vieira from skating around a high-rise.Jansen's family says he's now in an assisted living facility.