stephen hilburn haynesville alabama

It has recently come to me that Stephen Hilburn may have been a run a way slave.Stephen put on his naturalization application for Australia that he left America from California in 1857 on the ship the "What Cheer".He also states his parents were farmers John Hilburn and I think Sarah Parkes or Parker.If he were a run a way slave where would I find this information? Is it possible? Stephen would have been my Great Great Grandfather.

Merryll Martindale